81811554 has 16 divisors (see below), whose sum is σ = 178498080. Its totient is φ = 24791360.

The previous prime is 81811517. The next prime is 81811567. The reversal of 81811554 is 45511818.

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

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, 619719 + ... + 619850.

It is an arithmetic number, because the mean of its divisors is an integer number (11156130).

Almost surely, 2^81811554 is an apocalyptic number.

81811554 is an abundant number, since it is smaller than the sum of its proper divisors (96686526).

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

81811554 is a wasteful number, since it uses less digits than its factorization.

81811554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1239585.

The product of its digits is 6400, while the sum is 33.

The square root of 81811554 is about 9044.9739634783. The cubic root of 81811554 is about 434.1150883665.

The spelling of 81811554 in words is "eighty-one million, eight hundred eleven thousand, five hundred fifty-four".