81155690 has 32 divisors (see below), whose sum is σ = 182127744. Its totient is φ = 25295040.

The previous prime is 81155677. The next prime is 81155713. The reversal of 81155690 is 9655118.

It is a super-2 number, since 2×81155690² = 13172492038752200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 81155690.

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, 51929 + ... + 53468.

It is an arithmetic number, because the mean of its divisors is an integer number (5691492).

Almost surely, 2^81155690 is an apocalyptic number.

81155690 is an abundant number, since it is smaller than the sum of its proper divisors (100972054).

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

81155690 is a wasteful number, since it uses less digits than its factorization.

81155690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105422.

The product of its (nonzero) digits is 10800, while the sum is 35.

The square root of 81155690 is about 9008.6452921624. The cubic root of 81155690 is about 432.9519082822.

The spelling of 81155690 in words is "eighty-one million, one hundred fifty-five thousand, six hundred ninety".