21125106864 has 60 divisors (see below), whose sum is σ = 59869357600. Its totient is φ = 6952563072.

The previous prime is 21125106857. The next prime is 21125106911. The reversal of 21125106864 is 46860152112.

It is a happy number.

21125106864 is a `hidden beast` number, since 21 + 1 + 2 + 510 + 68 + 64 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 917119 + ... + 939870.

Almost surely, 2^21125106864 is an apocalyptic number.

21125106864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21125106864 is an abundant number, since it is smaller than the sum of its proper divisors (38744250736).

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

21125106864 is a wasteful number, since it uses less digits than its factorization.

21125106864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1857082 (or 1857073 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

Adding to 21125106864 its reverse (46860152112), we get a palindrome (67985258976).

The spelling of 21125106864 in words is "twenty-one billion, one hundred twenty-five million, one hundred six thousand, eight hundred sixty-four".