21051372188 has 24 divisors (see below), whose sum is σ = 45930267264. Its totient is φ = 8201833200.

The previous prime is 21051372179. The next prime is 21051372193. The reversal of 21051372188 is 88127315012.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 34173998 + ... + 34174613.

It is an arithmetic number, because the mean of its divisors is an integer number (1913761136).

Almost surely, 2^21051372188 is an apocalyptic number.

21051372188 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21051372188 is an abundant number, since it is smaller than the sum of its proper divisors (24878895076).

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

21051372188 is a wasteful number, since it uses less digits than its factorization.

21051372188 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68348633 (or 68348631 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 38.

The spelling of 21051372188 in words is "twenty-one billion, fifty-one million, three hundred seventy-two thousand, one hundred eighty-eight".