81776554 has 4 divisors (see below), whose sum is σ = 122664834. Its totient is φ = 40888276.

The previous prime is 81776531. The next prime is 81776567. The reversal of 81776554 is 45567718.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 41796225 + 39980329 = 6465^2 + 6323^2 .

It is a super-2 number, since 2×81776554² = 13374809568229832, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81776554.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20444137 + ... + 20444140.

Almost surely, 2^81776554 is an apocalyptic number.

81776554 is a deficient number, since it is larger than the sum of its proper divisors (40888280).

81776554 is a wasteful number, since it uses less digits than its factorization.

81776554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40888279.

The product of its digits is 235200, while the sum is 43.

The square root of 81776554 is about 9043.0389803428. The cubic root of 81776554 is about 434.0531729254.

The spelling of 81776554 in words is "eighty-one million, seven hundred seventy-six thousand, five hundred fifty-four".