21106513251 has 16 divisors (see below), whose sum is σ = 33108256800. Its totient is φ = 13243302144.

The previous prime is 21106513237. The next prime is 21106513271. The reversal of 21106513251 is 15231560112.

21106513251 is a `hidden beast` number, since 2 + 1 + 1 + 0 + 651 + 3 + 2 + 5 + 1 = 666.

It is not a de Polignac number, because 21106513251 - 2²² = 21102318947 is a prime.

It is a super-2 number, since 2×21106513251² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21106513271) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22991386 + ... + 22992303.

It is an arithmetic number, because the mean of its divisors is an integer number (2069266050).

Almost surely, 2^21106513251 is an apocalyptic number.

21106513251 is a deficient number, since it is larger than the sum of its proper divisors (12001743549).

21106513251 is a wasteful number, since it uses less digits than its factorization.

21106513251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45983715 (or 45983709 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 27.

The spelling of 21106513251 in words is "twenty-one billion, one hundred six million, five hundred thirteen thousand, two hundred fifty-one".