21690983 has 2 divisors, whose sum is σ = 21690984. Its totient is φ = 21690982.

The previous prime is 21690967. The next prime is 21691003. The reversal of 21690983 is 38909612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21690983 - 2⁴ = 21690967 is a prime.

It is a Sophie Germain prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21690943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10845491 + 10845492.

It is an arithmetic number, because the mean of its divisors is an integer number (10845492).

Almost surely, 2^21690983 is an apocalyptic number.

21690983 is a deficient number, since it is larger than the sum of its proper divisors (1).

21690983 is an equidigital number, since it uses as much as digits as its factorization.

21690983 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 21690983 is about 4657.3579420096. The cubic root of 21690983 is about 278.8858060525.

The spelling of 21690983 in words is "twenty-one million, six hundred ninety thousand, nine hundred eighty-three".