21507529851 has 6 divisors (see below), whose sum is σ = 31066432020. Its totient is φ = 14338353228.

The previous prime is 21507529843. The next prime is 21507529891. The reversal of 21507529851 is 15892570512.

21507529851 is a `hidden beast` number, since 2 + 1 + 507 + 5 + 2 + 98 + 51 = 666.

It is not a de Polignac number, because 21507529851 - 2³ = 21507529843 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21507529797 and 21507529806.

It is not an unprimeable number, because it can be changed into a prime (21507529801) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 1194862761 + ... + 1194862778.

It is an arithmetic number, because the mean of its divisors is an integer number (5177738670).

Almost surely, 2^21507529851 is an apocalyptic number.

21507529851 is a deficient number, since it is larger than the sum of its proper divisors (9558902169).

21507529851 is a wasteful number, since it uses less digits than its factorization.

21507529851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2389725545 (or 2389725542 counting only the distinct ones).

The product of its (nonzero) digits is 252000, while the sum is 45.

The spelling of 21507529851 in words is "twenty-one billion, five hundred seven million, five hundred twenty-nine thousand, eight hundred fifty-one".