21431624 has 16 divisors (see below), whose sum is σ = 41040000. Its totient is φ = 10487632.

The previous prime is 21431623. The next prime is 21431647. The reversal of 21431624 is 42613412.

It is a self number, because there is not a number n which added to its sum of digits gives 21431624.

It is not an unprimeable number, because it can be changed into a prime (21431623) 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, 28124 + ... + 28875.

It is an arithmetic number, because the mean of its divisors is an integer number (2565000).

Almost surely, 2^21431624 is an apocalyptic number.

It is an amenable number.

21431624 is a deficient number, since it is larger than the sum of its proper divisors (19608376).

21431624 is a wasteful number, since it uses less digits than its factorization.

21431624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57052 (or 57048 counting only the distinct ones).

The product of its digits is 1152, while the sum is 23.

The square root of 21431624 is about 4629.4302025195. The cubic root of 21431624 is about 277.7698006361.

The spelling of 21431624 in words is "twenty-one million, four hundred thirty-one thousand, six hundred twenty-four".