1643485540 has 48 divisors (see below), whose sum is σ = 3660524784. Its totient is φ = 617676800.

The previous prime is 1643485531. The next prime is 1643485567. The reversal of 1643485540 is 455843461.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 13264164 + 1630221376 = 3642^2 + 40376^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1643485493 and 1643485502.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 214170 + ... + 221710.

It is an arithmetic number, because the mean of its divisors is an integer number (76260933).

It is a vampire number, since it can be written as 30164 ⋅ 54485 (with its own digits).

Almost surely, 2^1643485540 is an apocalyptic number.

1643485540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1643485540 is the 25640-th heptagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1643485540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1830262392).

1643485540 is an abundant number, since it is smaller than the sum of its proper divisors (2017039244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1643485540 is a wasteful number, since it uses less digits than its factorization.

1643485540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8208 (or 8206 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 40.

The square root of 1643485540 is about 40539.9252589346. The cubic root of 1643485540 is about 1180.1085651333.

The spelling of 1643485540 in words is "one billion, six hundred forty-three million, four hundred eighty-five thousand, five hundred forty".