21379761 has 32 divisors (see below), whose sum is σ = 36126720. Its totient is φ = 12379392.

The previous prime is 21379759. The next prime is 21379763. The reversal of 21379761 is 16797312.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21379759) and next prime (21379763).

It is not a de Polignac number, because 21379761 - 2¹ = 21379759 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21379763) 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, 4176 + ... + 7758.

It is an arithmetic number, because the mean of its divisors is an integer number (1128960).

Almost surely, 2^21379761 is an apocalyptic number.

It is an amenable number.

21379761 is a deficient number, since it is larger than the sum of its proper divisors (14746959).

21379761 is a wasteful number, since it uses less digits than its factorization.

21379761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3622 (or 3616 counting only the distinct ones).

The product of its digits is 15876, while the sum is 36.

The square root of 21379761 is about 4623.8253643493. The cubic root of 21379761 is about 277.5455586266.

The spelling of 21379761 in words is "twenty-one million, three hundred seventy-nine thousand, seven hundred sixty-one".