81557742 has 16 divisors (see below), whose sum is σ = 186417792. Its totient is φ = 23302200.

The previous prime is 81557719. The next prime is 81557753. The reversal of 81557742 is 24775518.

It is a self number, because there is not a number n which added to its sum of digits gives 81557742.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 970884 + ... + 970967.

It is an arithmetic number, because the mean of its divisors is an integer number (11651112).

Almost surely, 2^81557742 is an apocalyptic number.

81557742 is an abundant number, since it is smaller than the sum of its proper divisors (104860050).

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

81557742 is a wasteful number, since it uses less digits than its factorization.

81557742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1941863.

The product of its digits is 78400, while the sum is 39.

The square root of 81557742 is about 9030.9325099903. The cubic root of 81557742 is about 433.6656907175.

The spelling of 81557742 in words is "eighty-one million, five hundred fifty-seven thousand, seven hundred forty-two".