21379637 has 4 divisors (see below), whose sum is σ = 21521376. Its totient is φ = 21237900.

The previous prime is 21379619. The next prime is 21379663. The reversal of 21379637 is 73697312.

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 21379637 - 2¹⁰ = 21378613 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21379637.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21379697) 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, 70643 + ... + 70944.

It is an arithmetic number, because the mean of its divisors is an integer number (5380344).

Almost surely, 2^21379637 is an apocalyptic number.

It is an amenable number.

21379637 is a deficient number, since it is larger than the sum of its proper divisors (141739).

21379637 is a wasteful number, since it uses less digits than its factorization.

21379637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141738.

The product of its digits is 47628, while the sum is 38.

The square root of 21379637 is about 4623.8119555190. The cubic root of 21379637 is about 277.5450220488.

The spelling of 21379637 in words is "twenty-one million, three hundred seventy-nine thousand, six hundred thirty-seven".