21987574 has 12 divisors (see below), whose sum is σ = 38366244. Its totient is φ = 9423204.

The previous prime is 21987571. The next prime is 21987601. The reversal of 21987574 is 47578912.

It is a self number, because there is not a number n which added to its sum of digits gives 21987574.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21987571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 112084 + ... + 112279.

It is an arithmetic number, because the mean of its divisors is an integer number (3197187).

Almost surely, 2^21987574 is an apocalyptic number.

21987574 is a deficient number, since it is larger than the sum of its proper divisors (16378670).

21987574 is a wasteful number, since it uses less digits than its factorization.

21987574 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 224379 (or 224372 counting only the distinct ones).

The product of its digits is 141120, while the sum is 43.

The square root of 21987574 is about 4689.0909566781. The cubic root of 21987574 is about 280.1511683715.

The spelling of 21987574 in words is "twenty-one million, nine hundred eighty-seven thousand, five hundred seventy-four".