21936961 has 2 divisors, whose sum is σ = 21936962. Its totient is φ = 21936960.

The previous prime is 21936931. The next prime is 21936973. The reversal of 21936961 is 16963912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18326961 + 3610000 = 4281^2 + 1900^2 .

It is a cyclic number.

It is not a de Polignac number, because 21936961 - 2⁷ = 21936833 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21936961.

It is not a weakly prime, because it can be changed into another prime (21936911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10968480 + 10968481.

It is an arithmetic number, because the mean of its divisors is an integer number (10968481).

Almost surely, 2^21936961 is an apocalyptic number.

It is an amenable number.

21936961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21936961 is an equidigital number, since it uses as much as digits as its factorization.

21936961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17496, while the sum is 37.

The square root of 21936961 is about 4683.6909590621. The cubic root of 21936961 is about 279.9360440661.

The spelling of 21936961 in words is "twenty-one million, nine hundred thirty-six thousand, nine hundred sixty-one".