21397974 has 16 divisors (see below), whose sum is σ = 46088112. Its totient is φ = 6583968.

The previous prime is 21397949. The next prime is 21397997. The reversal of 21397974 is 47979312.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 137089 + ... + 137244.

It is an arithmetic number, because the mean of its divisors is an integer number (2880507).

Almost surely, 2^21397974 is an apocalyptic number.

21397974 is an abundant number, since it is smaller than the sum of its proper divisors (24690138).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21397974 is a wasteful number, since it uses less digits than its factorization.

21397974 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274351.

The product of its digits is 95256, while the sum is 42.

The square root of 21397974 is about 4625.7944182594. The cubic root of 21397974 is about 277.6243481344.

The spelling of 21397974 in words is "twenty-one million, three hundred ninety-seven thousand, nine hundred seventy-four".