21670897 has 2 divisors, whose sum is σ = 21670898. Its totient is φ = 21670896.

The previous prime is 21670879. The next prime is 21670933. The reversal of 21670897 is 79807612.

Together with previous prime (21670879) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17969121 + 3701776 = 4239^2 + 1924^2 .

It is a cyclic number.

It is not a de Polignac number, because 21670897 - 2⁷ = 21670769 is a prime.

It is not a weakly prime, because it can be changed into another prime (21679897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10835448 + 10835449.

It is an arithmetic number, because the mean of its divisors is an integer number (10835449).

Almost surely, 2^21670897 is an apocalyptic number.

It is an amenable number.

21670897 is a deficient number, since it is larger than the sum of its proper divisors (1).

21670897 is an equidigital number, since it uses as much as digits as its factorization.

21670897 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 21670897 is about 4655.2010697713. The cubic root of 21670897 is about 278.7996960736.

The spelling of 21670897 in words is "twenty-one million, six hundred seventy thousand, eight hundred ninety-seven".