21696859 has 2 divisors, whose sum is σ = 21696860. Its totient is φ = 21696858.

The previous prime is 21696839. The next prime is 21696877. The reversal of 21696859 is 95869612.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21696859 is a prime.

It is a super-3 number, since 3×21696859³ (a number of 23 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21696809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10848429 + 10848430.

It is an arithmetic number, because the mean of its divisors is an integer number (10848430).

Almost surely, 2^21696859 is an apocalyptic number.

21696859 is a deficient number, since it is larger than the sum of its proper divisors (1).

21696859 is an equidigital number, since it uses as much as digits as its factorization.

21696859 is an evil number, because the sum of its binary digits is even.

The product of its digits is 233280, while the sum is 46.

The square root of 21696859 is about 4657.9887290546. The cubic root of 21696859 is about 278.9109867930.

The spelling of 21696859 in words is "twenty-one million, six hundred ninety-six thousand, eight hundred fifty-nine".