1643897025 has 135 divisors (see below), whose sum is σ = 3296907691. Its totient is φ = 809602560.

The previous prime is 1643896997. The next prime is 1643897027. The reversal of 1643897025 is 5207983461.

The square root of 1643897025 is 40545.

It is a perfect power (a square), and thus also a powerful number.

1643897025 is digitally balanced in base 10, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 13 ways, for example, as 252905409 + 1390991616 = 15903^2 + 37296^2 .

It is a tau number, because it is divible by the number of its divisors (135).

It is not a de Polignac number, because 1643897025 - 2¹¹ = 1643894977 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Duffinian number.

1643897025 is strictly pandigital in base 10.

It is not an unprimeable number, because it can be changed into a prime (1643897027) by changing a digit.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 31016899 + ... + 31016951.

It is a 1-persistent number, because it is pandigital, but 2⋅1643897025 = 3287794050 is not.

Almost surely, 2^1643897025 is an apocalyptic number.

1643897025 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1643897025 is the 40545-th square number and also the 23409-th octagonal number.

1643897025 is the 20273-rd centered octagonal number.

It is an amenable number.

1643897025 is an abundant number, since it is smaller than the sum of its proper divisors (1653010666).

1643897025 is an equidigital number, since it uses as much as digits as its factorization.

1643897025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162 (or 78 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The cubic root of 1643897025 is about 1180.2070461644.

The spelling of 1643897025 in words is "one billion, six hundred forty-three million, eight hundred ninety-seven thousand, twenty-five".