21216210651 has 24 divisors (see below), whose sum is σ = 30885167040. Its totient is φ = 14033715696.

The previous prime is 21216210623. The next prime is 21216210661. The reversal of 21216210651 is 15601261212.

21216210651 is a `hidden beast` number, since 2 + 1 + 2 + 1 + 6 + 2 + 1 + 0 + 651 = 666.

It is not a de Polignac number, because 21216210651 - 2⁵ = 21216210619 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21216210661) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2501520 + ... + 2509986.

It is an arithmetic number, because the mean of its divisors is an integer number (1286881960).

Almost surely, 2^21216210651 is an apocalyptic number.

21216210651 is a deficient number, since it is larger than the sum of its proper divisors (9668956389).

21216210651 is a wasteful number, since it uses less digits than its factorization.

21216210651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10615 (or 10612 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

Adding to 21216210651 its reverse (15601261212), we get a palindrome (36817471863).

The spelling of 21216210651 in words is "twenty-one billion, two hundred sixteen million, two hundred ten thousand, six hundred fifty-one".