21631671 has 32 divisors (see below), whose sum is σ = 34080000. Its totient is φ = 13522464.

The previous prime is 21631663. The next prime is 21631691. The reversal of 21631671 is 17613612.

21631671 is a `hidden beast` number, since 21 + 631 + 6 + 7 + 1 = 666.

It is not a de Polignac number, because 21631671 - 2³ = 21631663 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21631691) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 76296 + ... + 76578.

It is an arithmetic number, because the mean of its divisors is an integer number (1065000).

Almost surely, 2^21631671 is an apocalyptic number.

21631671 is a deficient number, since it is larger than the sum of its proper divisors (12448329).

21631671 is a wasteful number, since it uses less digits than its factorization.

21631671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 460 (or 454 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 21631671 is about 4650.9860244899. The cubic root of 21631671 is about 278.6313781374.

The spelling of 21631671 in words is "twenty-one million, six hundred thirty-one thousand, six hundred seventy-one".