21936973 has 2 divisors, whose sum is σ = 21936974. Its totient is φ = 21936972.

The previous prime is 21936961. The next prime is 21936977. The reversal of 21936973 is 37963912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20766249 + 1170724 = 4557^2 + 1082^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21936973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21936977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10968486 + 10968487.

It is an arithmetic number, because the mean of its divisors is an integer number (10968487).

Almost surely, 2^21936973 is an apocalyptic number.

It is an amenable number.

21936973 is a deficient number, since it is larger than the sum of its proper divisors (1).

21936973 is an equidigital number, since it uses as much as digits as its factorization.

21936973 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 61236, while the sum is 40.

The square root of 21936973 is about 4683.6922401029. The cubic root of 21936973 is about 279.9360951099.

The spelling of 21936973 in words is "twenty-one million, nine hundred thirty-six thousand, nine hundred seventy-three".