21961879 has 2 divisors, whose sum is σ = 21961880. Its totient is φ = 21961878.

The previous prime is 21961873. The next prime is 21961897. The reversal of 21961879 is 97816912.

Together with next prime (21961897) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21961879 - 2⁵ = 21961847 is a prime.

It is a pancake number, because a pancake can be divided into 21961879 parts by 6627 straight cuts.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21961873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10980939 + 10980940.

It is an arithmetic number, because the mean of its divisors is an integer number (10980940).

Almost surely, 2^21961879 is an apocalyptic number.

21961879 is a deficient number, since it is larger than the sum of its proper divisors (1).

21961879 is an equidigital number, since it uses as much as digits as its factorization.

21961879 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 43.

The square root of 21961879 is about 4686.3502856701. The cubic root of 21961879 is about 280.0419962518.

The spelling of 21961879 in words is "twenty-one million, nine hundred sixty-one thousand, eight hundred seventy-nine".