21131686512 has 40 divisors (see below), whose sum is σ = 60655768080. Its totient is φ = 7043895360.

The previous prime is 21131686507. The next prime is 21131686547. The reversal of 21131686512 is 21568613112.

21131686512 is a `hidden beast` number, since 2 + 1 + 131 + 6 + 8 + 6 + 512 = 666.

It is a super-2 number, since 2×21131686512² (a number of 21 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24457539 + ... + 24458402.

It is an arithmetic number, because the mean of its divisors is an integer number (1516394202).

Almost surely, 2^21131686512 is an apocalyptic number.

It is an amenable number.

21131686512 is an abundant number, since it is smaller than the sum of its proper divisors (39524081568).

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

21131686512 is a wasteful number, since it uses less digits than its factorization.

21131686512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48915958 (or 48915946 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The spelling of 21131686512 in words is "twenty-one billion, one hundred thirty-one million, six hundred eighty-six thousand, five hundred twelve".