21931242 has 16 divisors (see below), whose sum is σ = 43911552. Its totient is φ = 7302240.

The previous prime is 21931237. The next prime is 21931243. The reversal of 21931242 is 24213912.

It is not an unprimeable number, because it can be changed into a prime (21931243) 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 7 ways as a sum of consecutive naturals, for example, 6543 + ... + 9309.

It is an arithmetic number, because the mean of its divisors is an integer number (2744472).

Almost surely, 2^21931242 is an apocalyptic number.

21931242 is an abundant number, since it is smaller than the sum of its proper divisors (21980310).

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

21931242 is a wasteful number, since it uses less digits than its factorization.

21931242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4093.

The product of its digits is 864, while the sum is 24.

The square root of 21931242 is about 4683.0803964912. The cubic root of 21931242 is about 279.9117153639.

The spelling of 21931242 in words is "twenty-one million, nine hundred thirty-one thousand, two hundred forty-two".