20916531 has 12 divisors (see below), whose sum is σ = 30259008. Its totient is φ = 13923024.

The previous prime is 20916527. The next prime is 20916557. The reversal of 20916531 is 13561902.

20916531 is a `hidden beast` number, since 2 + 0 + 9 + 1 + 653 + 1 = 666.

It is not a de Polignac number, because 20916531 - 2² = 20916527 is a prime.

It is a super-5 number, since 5×20916531⁵ (a number of 38 digits) contains 55555 as substring. Note that it is a super-d number also for d = 2.

It is a junction number, because it is equal to n+sod(n) for n = 20916495 and 20916504.

It is not an unprimeable number, because it can be changed into a prime (20916521) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6421 + ... + 9113.

It is an arithmetic number, because the mean of its divisors is an integer number (2521584).

Almost surely, 2^20916531 is an apocalyptic number.

20916531 is a deficient number, since it is larger than the sum of its proper divisors (9342477).

20916531 is a wasteful number, since it uses less digits than its factorization.

20916531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3562 (or 3559 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 27.

The square root of 20916531 is about 4573.4594127422. The cubic root of 20916531 is about 275.5264010940.

The spelling of 20916531 in words is "twenty million, nine hundred sixteen thousand, five hundred thirty-one".