21802961 has 2 divisors, whose sum is σ = 21802962. Its totient is φ = 21802960.

The previous prime is 21802931. The next prime is 21802987. The reversal of 21802961 is 16920812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17472400 + 4330561 = 4180^2 + 2081^2 .

It is a cyclic number.

It is not a de Polignac number, because 21802961 - 2⁶ = 21802897 is a prime.

It is not a weakly prime, because it can be changed into another prime (21802901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10901480 + 10901481.

It is an arithmetic number, because the mean of its divisors is an integer number (10901481).

Almost surely, 2^21802961 is an apocalyptic number.

It is an amenable number.

21802961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21802961 is an equidigital number, since it uses as much as digits as its factorization.

21802961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 21802961 is about 4669.3640894666. The cubic root of 21802961 is about 279.3648912891.

The spelling of 21802961 in words is "twenty-one million, eight hundred two thousand, nine hundred sixty-one".