21919437 has 32 divisors (see below), whose sum is σ = 34652160. Its totient is φ = 13662000.

The previous prime is 21919433. The next prime is 21919439. The reversal of 21919437 is 73491912.

21919437 is a `hidden beast` number, since 219 + 1 + 9 + 437 = 666.

It is not a de Polignac number, because 21919437 - 2² = 21919433 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21919433) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28812 + ... + 29562.

It is an arithmetic number, because the mean of its divisors is an integer number (1082880).

Almost surely, 2^21919437 is an apocalyptic number.

21919437 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21919437 is a deficient number, since it is larger than the sum of its proper divisors (12732723).

21919437 is a wasteful number, since it uses less digits than its factorization.

21919437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 830 (or 824 counting only the distinct ones).

The product of its digits is 13608, while the sum is 36.

The square root of 21919437 is about 4681.8198384816. The cubic root of 21919437 is about 279.8614833575.

It can be divided in two parts, 2191 and 9437, that added together give a triangular number (11628 = T₁₅₂).

The spelling of 21919437 in words is "twenty-one million, nine hundred nineteen thousand, four hundred thirty-seven".