81506374 has 4 divisors (see below), whose sum is σ = 122259564. Its totient is φ = 40753186.

The previous prime is 81506363. The next prime is 81506377. The reversal of 81506374 is 47360518.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81506377) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20376592 + ... + 20376595.

It is an arithmetic number, because the mean of its divisors is an integer number (30564891).

Almost surely, 2^81506374 is an apocalyptic number.

81506374 is a deficient number, since it is larger than the sum of its proper divisors (40753190).

81506374 is a wasteful number, since it uses less digits than its factorization.

81506374 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40753189.

The product of its (nonzero) digits is 20160, while the sum is 34.

The square root of 81506374 is about 9028.0880589414. The cubic root of 81506374 is about 433.5746255116.

The spelling of 81506374 in words is "eighty-one million, five hundred six thousand, three hundred seventy-four".