81931740 has 48 divisors (see below), whose sum is σ = 250266240. Its totient is φ = 19862080.

The previous prime is 81931711. The next prime is 81931753. The reversal of 81931740 is 4713918.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 61410 + ... + 62729.

It is an arithmetic number, because the mean of its divisors is an integer number (5213880).

Almost surely, 2^81931740 is an apocalyptic number.

It is an amenable number.

81931740 is an abundant number, since it is smaller than the sum of its proper divisors (168334500).

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

81931740 is a wasteful number, since it uses less digits than its factorization.

81931740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124162 (or 124160 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 33.

The square root of 81931740 is about 9051.6153254543. The cubic root of 81931740 is about 434.3275645801.

The spelling of 81931740 in words is "eighty-one million, nine hundred thirty-one thousand, seven hundred forty".