81391674 has 32 divisors (see below), whose sum is σ = 200350080. Its totient is φ = 21465792.

The previous prime is 81391669. The next prime is 81391679. The reversal of 81391674 is 47619318.

It is an interprime number because it is at equal distance from previous prime (81391669) and next prime (81391679).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81391679) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 73989 + ... + 75080.

It is an arithmetic number, because the mean of its divisors is an integer number (6260940).

Almost surely, 2^81391674 is an apocalyptic number.

81391674 is an abundant number, since it is smaller than the sum of its proper divisors (118958406).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81391674 is a wasteful number, since it uses less digits than its factorization.

81391674 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149094.

The product of its digits is 36288, while the sum is 39.

The square root of 81391674 is about 9021.7334254566. The cubic root of 81391674 is about 433.3711471275.

The spelling of 81391674 in words is "eighty-one million, three hundred ninety-one thousand, six hundred seventy-four".