21216562156 has 12 divisors (see below), whose sum is σ = 39313041768. Its totient is φ = 9984264512.

The previous prime is 21216562151. The next prime is 21216562177. The reversal of 21216562156 is 65126561212.

It is a super-2 number, since 2×21216562156² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21216562151) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 156004066 + ... + 156004201.

It is an arithmetic number, because the mean of its divisors is an integer number (3276086814).

Almost surely, 2^21216562156 is an apocalyptic number.

It is an amenable number.

21216562156 is a deficient number, since it is larger than the sum of its proper divisors (18096479612).

21216562156 is a wasteful number, since it uses less digits than its factorization.

21216562156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312008288 (or 312008286 counting only the distinct ones).

The product of its digits is 43200, while the sum is 37.

The spelling of 21216562156 in words is "twenty-one billion, two hundred sixteen million, five hundred sixty-two thousand, one hundred fifty-six".