21164450625 has 60 divisors (see below), whose sum is σ = 38314376100. Its totient is φ = 11254320000.

The previous prime is 21164450597. The next prime is 21164450639. The reversal of 21164450625 is 52605446112.

21164450625 is a `hidden beast` number, since 2 + 1 + 1 + 644 + 5 + 0 + 6 + 2 + 5 = 666.

It can be written as a sum of positive squares in 10 ways, for example, as 16054917264 + 5109533361 = 126708^2 + 71481^2 .

It is not a de Polignac number, because 21164450625 - 2⁶ = 21164450561 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21164450625.

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 1957735 + ... + 1968515.

It is an arithmetic number, because the mean of its divisors is an integer number (638572935).

Almost surely, 2^21164450625 is an apocalyptic number.

21164450625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21164450625 is a deficient number, since it is larger than the sum of its proper divisors (17149925475).

21164450625 is a wasteful number, since it uses less digits than its factorization.

21164450625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11156 (or 11138 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

Adding to 21164450625 its reverse (52605446112), we get a palindrome (73769896737).

The spelling of 21164450625 in words is "twenty-one billion, one hundred sixty-four million, four hundred fifty thousand, six hundred twenty-five".