81977897 has 2 divisors, whose sum is σ = 81977898. Its totient is φ = 81977896.

The previous prime is 81977887. The next prime is 81977921. The reversal of 81977897 is 79877918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61763881 + 20214016 = 7859^2 + 4496^2 .

It is a cyclic number.

It is not a de Polignac number, because 81977897 - 2⁸ = 81977641 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81977827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40988948 + 40988949.

It is an arithmetic number, because the mean of its divisors is an integer number (40988949).

Almost surely, 2^81977897 is an apocalyptic number.

It is an amenable number.

81977897 is a deficient number, since it is larger than the sum of its proper divisors (1).

81977897 is an equidigital number, since it uses as much as digits as its factorization.

81977897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1778112, while the sum is 56.

The square root of 81977897 is about 9054.1646218743. The cubic root of 81977897 is about 434.4091100795.

The spelling of 81977897 in words is "eighty-one million, nine hundred seventy-seven thousand, eight hundred ninety-seven".