21812977 has 2 divisors, whose sum is σ = 21812978. Its totient is φ = 21812976.

The previous prime is 21812953. The next prime is 21812983. The reversal of 21812977 is 77921812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21307456 + 505521 = 4616^2 + 711^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21812977 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21882977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10906488 + 10906489.

It is an arithmetic number, because the mean of its divisors is an integer number (10906489).

Almost surely, 2^21812977 is an apocalyptic number.

It is an amenable number.

21812977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21812977 is an equidigital number, since it uses as much as digits as its factorization.

21812977 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14112, while the sum is 37.

The square root of 21812977 is about 4670.4364892374. The cubic root of 21812977 is about 279.4076636200.

The spelling of 21812977 in words is "twenty-one million, eight hundred twelve thousand, nine hundred seventy-seven".