81757997 has 2 divisors, whose sum is σ = 81757998. Its totient is φ = 81757996.

The previous prime is 81757927. The next prime is 81757999. The reversal of 81757997 is 79975718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 74200996 + 7557001 = 8614^2 + 2749^2 .

It is a cyclic number.

It is not a de Polignac number, because 81757997 - 2¹⁴ = 81741613 is a prime.

Together with 81757999, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81757999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40878998 + 40878999.

It is an arithmetic number, because the mean of its divisors is an integer number (40878999).

Almost surely, 2^81757997 is an apocalyptic number.

It is an amenable number.

81757997 is a deficient number, since it is larger than the sum of its proper divisors (1).

81757997 is an equidigital number, since it uses as much as digits as its factorization.

81757997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1111320, while the sum is 53.

The square root of 81757997 is about 9042.0128843084. The cubic root of 81757997 is about 434.0203381919.

The spelling of 81757997 in words is "eighty-one million, seven hundred fifty-seven thousand, nine hundred ninety-seven".