21437919 has 16 divisors (see below), whose sum is σ = 31891200. Its totient is φ = 14232888.

The previous prime is 21437893. The next prime is 21437921. The reversal of 21437919 is 91973412.

It is not a de Polignac number, because 21437919 - 2⁵ = 21437887 is a prime.

It is a super-2 number, since 2×21437919² = 919168742101122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21437939) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5592 + ... + 8610.

It is an arithmetic number, because the mean of its divisors is an integer number (1993200).

Almost surely, 2^21437919 is an apocalyptic number.

21437919 is a deficient number, since it is larger than the sum of its proper divisors (10453281).

21437919 is a wasteful number, since it uses less digits than its factorization.

21437919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3291 (or 3285 counting only the distinct ones).

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

The square root of 21437919 is about 4630.1100418889. The cubic root of 21437919 is about 277.7969939358.

The spelling of 21437919 in words is "twenty-one million, four hundred thirty-seven thousand, nine hundred nineteen".