21379807 has 4 divisors (see below), whose sum is σ = 22505080. Its totient is φ = 20254536.

The previous prime is 21379763. The next prime is 21379817. The reversal of 21379807 is 70897312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21379807 - 2¹⁹ = 20855519 is a prime.

It is a super-2 number, since 2×21379807² = 914192294714498, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21379817) 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, 562608 + ... + 562645.

It is an arithmetic number, because the mean of its divisors is an integer number (5626270).

Almost surely, 2^21379807 is an apocalyptic number.

21379807 is a deficient number, since it is larger than the sum of its proper divisors (1125273).

21379807 is a wasteful number, since it uses less digits than its factorization.

21379807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1125272.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 21379807 is about 4623.8303385829. The cubic root of 21379807 is about 277.5457576792.

The spelling of 21379807 in words is "twenty-one million, three hundred seventy-nine thousand, eight hundred seven".