21537474 has 16 divisors (see below), whose sum is σ = 49228608. Its totient is φ = 6153552.

The previous prime is 21537473. The next prime is 21537479. The reversal of 21537474 is 47473512.

It is not an unprimeable number, because it can be changed into a prime (21537473) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 256357 + ... + 256440.

It is an arithmetic number, because the mean of its divisors is an integer number (3076788).

Almost surely, 2^21537474 is an apocalyptic number.

21537474 is an abundant number, since it is smaller than the sum of its proper divisors (27691134).

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

21537474 is a wasteful number, since it uses less digits than its factorization.

21537474 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 512809.

The product of its digits is 23520, while the sum is 33.

The square root of 21537474 is about 4640.8484138140. The cubic root of 21537474 is about 278.2263481001.

The spelling of 21537474 in words is "twenty-one million, five hundred thirty-seven thousand, four hundred seventy-four".