81635257 has 8 divisors (see below), whose sum is σ = 92928960. Its totient is φ = 70986960.

The previous prime is 81635233. The next prime is 81635293. The reversal of 81635257 is 75253618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81635257 - 2⁷ = 81635129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81635857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161082 + ... + 161587.

It is an arithmetic number, because the mean of its divisors is an integer number (11616120).

Almost surely, 2^81635257 is an apocalyptic number.

It is an amenable number.

81635257 is a deficient number, since it is larger than the sum of its proper divisors (11293703).

81635257 is a wasteful number, since it uses less digits than its factorization.

81635257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322703.

The product of its digits is 50400, while the sum is 37.

The square root of 81635257 is about 9035.2231295082. The cubic root of 81635257 is about 433.8030369748.

The spelling of 81635257 in words is "eighty-one million, six hundred thirty-five thousand, two hundred fifty-seven".