20091645025 has 9 divisors (see below), whose sum is σ = 24914518681. Its totient is φ = 16072749040.

The previous prime is 20091644971. The next prime is 20091645029. The reversal of 20091645025 is 52054619002.

It is a happy number.

The square root of 20091645025 is 141745.

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

It can be written as a sum of positive squares in 4 ways, for example, as 9011135329 + 11080509696 = 94927^2 + 105264^2 .

It is not a de Polignac number, because 20091645025 - 2¹⁹ = 20091120737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20091645029) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 694551 + ... + 722899.

Almost surely, 2^20091645025 is an apocalyptic number.

20091645025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

20091645025 is the 141745-th square number.

20091645025 is the 70873-rd centered octagonal number.

It is an amenable number.

20091645025 is a deficient number, since it is larger than the sum of its proper divisors (4822873656).

20091645025 is an frugal number, since it uses more digits than its factorization.

20091645025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56708 (or 28354 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 34.

The spelling of 20091645025 in words is "twenty billion, ninety-one million, six hundred forty-five thousand, twenty-five".