21379537 has 4 divisors (see below), whose sum is σ = 21389040. Its totient is φ = 21370036.

The previous prime is 21379531. The next prime is 21379543. The reversal of 21379537 is 73597312.

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, and also a brilliant number, because the two primes have the same length.

It is an interprime number because it is at equal distance from previous prime (21379531) and next prime (21379543).

It is a cyclic number.

It is not a de Polignac number, because 21379537 - 2¹⁹ = 20855249 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21379496 and 21379505.

It is not an unprimeable number, because it can be changed into a prime (21379531) 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, 738 + ... + 6580.

It is an arithmetic number, because the mean of its divisors is an integer number (5347260).

Almost surely, 2^21379537 is an apocalyptic number.

It is an amenable number.

21379537 is a deficient number, since it is larger than the sum of its proper divisors (9503).

21379537 is an equidigital number, since it uses as much as digits as its factorization.

21379537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9502.

The product of its digits is 39690, while the sum is 37.

The square root of 21379537 is about 4623.8011419178. The cubic root of 21379537 is about 277.5445893233.

The spelling of 21379537 in words is "twenty-one million, three hundred seventy-nine thousand, five hundred thirty-seven".