21437929 has 4 divisors (see below), whose sum is σ = 21471120. Its totient is φ = 21404740.

The previous prime is 21437921. The next prime is 21437939. The reversal of 21437929 is 92973412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21437929 - 2³ = 21437921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21437921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15607 + ... + 16924.

It is an arithmetic number, because the mean of its divisors is an integer number (5367780).

Almost surely, 2^21437929 is an apocalyptic number.

It is an amenable number.

21437929 is a deficient number, since it is larger than the sum of its proper divisors (33191).

21437929 is an equidigital number, since it uses as much as digits as its factorization.

21437929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33190.

The product of its digits is 27216, while the sum is 37.

The square root of 21437929 is about 4630.1111217767. Note that the first 4 decimals coincide. The cubic root of 21437929 is about 277.7970371298.

It can be divided in two parts, 21437 and 929, that added together give a triangular number (22366 = T₂₁₁).

The spelling of 21437929 in words is "twenty-one million, four hundred thirty-seven thousand, nine hundred twenty-nine".