21931492 has 36 divisors (see below), whose sum is σ = 42665868. Its totient is φ = 9856000.

The previous prime is 21931451. The next prime is 21931499. The reversal of 21931492 is 29413912.

It can be written as a sum of positive squares in 2 ways, for example, as 11329956 + 10601536 = 3366^2 + 3256^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21931499) 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 11 ways as a sum of consecutive naturals, for example, 54492 + ... + 54892.

It is an arithmetic number, because the mean of its divisors is an integer number (1185163).

Almost surely, 2^21931492 is an apocalyptic number.

21931492 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21931492 is a deficient number, since it is larger than the sum of its proper divisors (20734376).

21931492 is a wasteful number, since it uses less digits than its factorization.

21931492 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 540 (or 527 counting only the distinct ones).

The product of its digits is 3888, while the sum is 31.

The square root of 21931492 is about 4683.1070882481. The cubic root of 21931492 is about 279.9127789556.

The spelling of 21931492 in words is "twenty-one million, nine hundred thirty-one thousand, four hundred ninety-two".