21986679 has 32 divisors (see below), whose sum is σ = 35126784. Its totient is φ = 12055680.

The previous prime is 21986639. The next prime is 21986683. The reversal of 21986679 is 97668912.

It is not a de Polignac number, because 21986679 - 2¹¹ = 21984631 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21986609) 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, 22254 + ... + 23220.

It is an arithmetic number, because the mean of its divisors is an integer number (1097712).

Almost surely, 2^21986679 is an apocalyptic number.

21986679 is a deficient number, since it is larger than the sum of its proper divisors (13140105).

21986679 is a wasteful number, since it uses less digits than its factorization.

21986679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1047.

The product of its digits is 326592, while the sum is 48.

The square root of 21986679 is about 4688.9955214310. The cubic root of 21986679 is about 280.1473671533.

The spelling of 21986679 in words is "twenty-one million, nine hundred eighty-six thousand, six hundred seventy-nine".