21278632856 has 32 divisors (see below), whose sum is σ = 43280123040. Its totient is φ = 9749215488.

The previous prime is 21278632831. The next prime is 21278632871. The reversal of 21278632856 is 65823687212.

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, 732476 + ... + 760971.

It is an arithmetic number, because the mean of its divisors is an integer number (1352503845).

Almost surely, 2^21278632856 is an apocalyptic number.

21278632856 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21278632856 is an abundant number, since it is smaller than the sum of its proper divisors (22001490184).

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

21278632856 is a wasteful number, since it uses less digits than its factorization.

21278632856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1493603 (or 1493599 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 50.

The spelling of 21278632856 in words is "twenty-one billion, two hundred seventy-eight million, six hundred thirty-two thousand, eight hundred fifty-six".