21670879 has 2 divisors, whose sum is σ = 21670880. Its totient is φ = 21670878.

The previous prime is 21670871. The next prime is 21670897. The reversal of 21670879 is 97807612.

Together with next prime (21670897) 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 21670879 - 2³ = 21670871 is a prime.

It is a Chen prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21670871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10835439 + 10835440.

It is an arithmetic number, because the mean of its divisors is an integer number (10835440).

Almost surely, 2^21670879 is an apocalyptic number.

21670879 is a deficient number, since it is larger than the sum of its proper divisors (1).

21670879 is an equidigital number, since it uses as much as digits as its factorization.

21670879 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 42336, while the sum is 40.

The square root of 21670879 is about 4655.1991364495. The cubic root of 21670879 is about 278.7996188826.

The spelling of 21670879 in words is "twenty-one million, six hundred seventy thousand, eight hundred seventy-nine".