81787392 has 60 divisors (see below), whose sum is σ = 236057250. Its totient is φ = 27260928.

The previous prime is 81787327. The next prime is 81787399. The reversal of 81787392 is 29378718.

It can be written as a sum of positive squares in only one way, i.e., 80568576 + 1218816 = 8976^2 + 1104^2 .

It is not an unprimeable number, because it can be changed into a prime (81787399) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4267 + ... + 13482.

Almost surely, 2^81787392 is an apocalyptic number.

It is an amenable number.

81787392 is an abundant number, since it is smaller than the sum of its proper divisors (154269858).

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

81787392 is a wasteful number, since it uses less digits than its factorization.

81787392 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17773 (or 17754 counting only the distinct ones).

The product of its digits is 169344, while the sum is 45.

The square root of 81787392 is about 9043.6382059434. The cubic root of 81787392 is about 434.0723473719.

It can be divided in two parts, 817 and 87392, that added together give a square (88209 = 297²).

The spelling of 81787392 in words is "eighty-one million, seven hundred eighty-seven thousand, three hundred ninety-two".