20731680225 has 81 divisors (see below), whose sum is σ = 38573871609. Its totient is φ = 10643371200.

The previous prime is 20731680199. The next prime is 20731680227. The reversal of 20731680225 is 52208613702.

The square root of 20731680225 is 143985.

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 284968161 + 20446712064 = 16881^2 + 142992^2 .

It is not a de Polignac number, because 20731680225 - 2⁹ = 20731679713 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20731680225.

It is not an unprimeable number, because it can be changed into a prime (20731680227) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 62633310 + ... + 62633640.

Almost surely, 2^20731680225 is an apocalyptic number.

20731680225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

20731680225 is the 143985-th square number.

20731680225 is the 71993-rd centered octagonal number.

It is an amenable number.

20731680225 is a deficient number, since it is larger than the sum of its proper divisors (17842191384).

20731680225 is an equidigital number, since it uses as much as digits as its factorization.

20731680225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 736 (or 368 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

Multiplying 20731680225 by its sum of digits (36), we get a square (746340488100 = 863910²).

The spelling of 20731680225 in words is "twenty billion, seven hundred thirty-one million, six hundred eighty thousand, two hundred twenty-five".