21955679 has 4 divisors (see below), whose sum is σ = 21966000. Its totient is φ = 21945360.

The previous prime is 21955673. The next prime is 21955691. The reversal of 21955679 is 97655912.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21955679 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21955673) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 662 + ... + 6659.

It is an arithmetic number, because the mean of its divisors is an integer number (5491500).

Almost surely, 2^21955679 is an apocalyptic number.

21955679 is a deficient number, since it is larger than the sum of its proper divisors (10321).

21955679 is an equidigital number, since it uses as much as digits as its factorization.

21955679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10320.

The product of its digits is 170100, while the sum is 44.

The square root of 21955679 is about 4685.6887433973. The cubic root of 21955679 is about 280.0156411331.

The spelling of 21955679 in words is "twenty-one million, nine hundred fifty-five thousand, six hundred seventy-nine".