21239542 has 8 divisors (see below), whose sum is σ = 32958000. Its totient is φ = 10253544.

The previous prime is 21239507. The next prime is 21239551. The reversal of 21239542 is 24593212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21239542² = 902236288739528, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21239542.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 183042 + ... + 183157.

It is an arithmetic number, because the mean of its divisors is an integer number (4119750).

Almost surely, 2^21239542 is an apocalyptic number.

21239542 is a deficient number, since it is larger than the sum of its proper divisors (11718458).

21239542 is a wasteful number, since it uses less digits than its factorization.

21239542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366230.

The product of its digits is 4320, while the sum is 28.

The square root of 21239542 is about 4608.6377596856. The cubic root of 21239542 is about 276.9374671495.

The spelling of 21239542 in words is "twenty-one million, two hundred thirty-nine thousand, five hundred forty-two".