21977953 has 2 divisors, whose sum is σ = 21977954. Its totient is φ = 21977952.

The previous prime is 21977941. The next prime is 21977993. The reversal of 21977953 is 35977912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18939904 + 3038049 = 4352^2 + 1743^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21977953 is a prime.

It is not a weakly prime, because it can be changed into another prime (21977933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10988976 + 10988977.

It is an arithmetic number, because the mean of its divisors is an integer number (10988977).

Almost surely, 2^21977953 is an apocalyptic number.

It is an amenable number.

21977953 is a deficient number, since it is larger than the sum of its proper divisors (1).

21977953 is an equidigital number, since it uses as much as digits as its factorization.

21977953 is an evil number, because the sum of its binary digits is even.

The product of its digits is 119070, while the sum is 43.

The square root of 21977953 is about 4688.0649526217. The cubic root of 21977953 is about 280.1103009310.

The spelling of 21977953 in words is "twenty-one million, nine hundred seventy-seven thousand, nine hundred fifty-three".