19640621025 has 27 divisors (see below), whose sum is σ = 35182300179. Its totient is φ = 10473876720.

The previous prime is 19640620963. The next prime is 19640621041. The reversal of 19640621025 is 52012604691.

The square root of 19640621025 is 140145.

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

19640621025 is a `hidden beast` number, since 1 + 9 + 6 + 4 + 0 + 621 + 0 + 25 = 666.

It can be written as a sum of positive squares in only one way, i.e., 7070623569 + 12569997456 = 84087^2 + 112116^2 .

It is not a de Polignac number, because 19640621025 - 2²⁷ = 19506403297 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 2097504 + ... + 2106846.

Almost surely, 2^19640621025 is an apocalyptic number.

19640621025 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

19640621025 is the 140145-th square number.

19640621025 is the 70073-rd centered octagonal number.

It is an amenable number.

19640621025 is a deficient number, since it is larger than the sum of its proper divisors (15541679154).

19640621025 is an frugal number, since it uses more digits than its factorization.

19640621025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18702 (or 9351 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

Multiplying 19640621025 by its sum of digits (36), we get a square (707062356900 = 840870²).

The spelling of 19640621025 in words is "nineteen billion, six hundred forty million, six hundred twenty-one thousand, twenty-five".