81742572 has 18 divisors (see below), whose sum is σ = 206627148. Its totient is φ = 27247512.

The previous prime is 81742547. The next prime is 81742597. The reversal of 81742572 is 27524718.

81742572 is a `hidden beast` number, since 81 + 7 + 4 + 2 + 572 = 666.

It is an interprime number because it is at equal distance from previous prime (81742547) and next prime (81742597).

It is a tau number, because it is divible by the number of its divisors (18).

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 2270627 = 81742572 / (8 + 1 + 7 + 4 + 2 + 5 + 7 + 2).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1135278 + ... + 1135349.

It is an arithmetic number, because the mean of its divisors is an integer number (11479286).

Almost surely, 2^81742572 is an apocalyptic number.

It is an amenable number.

81742572 is an abundant number, since it is smaller than the sum of its proper divisors (124884576).

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

81742572 is a wasteful number, since it uses less digits than its factorization.

81742572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2270637 (or 2270632 counting only the distinct ones).

The product of its digits is 31360, while the sum is 36.

The square root of 81742572 is about 9041.1598813427. The cubic root of 81742572 is about 433.9930414339.

The spelling of 81742572 in words is "eighty-one million, seven hundred forty-two thousand, five hundred seventy-two".