81633857 has 2 divisors, whose sum is σ = 81633858. Its totient is φ = 81633856.

The previous prime is 81633821. The next prime is 81633863. The reversal of 81633857 is 75833618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62980096 + 18653761 = 7936^2 + 4319^2 .

It is a cyclic number.

It is not a de Polignac number, because 81633857 - 2⁶ = 81633793 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81633817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40816928 + 40816929.

It is an arithmetic number, because the mean of its divisors is an integer number (40816929).

Almost surely, 2^81633857 is an apocalyptic number.

It is an amenable number.

81633857 is a deficient number, since it is larger than the sum of its proper divisors (1).

81633857 is an equidigital number, since it uses as much as digits as its factorization.

81633857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120960, while the sum is 41.

The square root of 81633857 is about 9035.1456546090. The cubic root of 81633857 is about 433.8005571324.

The spelling of 81633857 in words is "eighty-one million, six hundred thirty-three thousand, eight hundred fifty-seven".