81555554 has 8 divisors (see below), whose sum is σ = 122453100. Its totient is φ = 40737856.

The previous prime is 81555547. The next prime is 81555557. The reversal of 81555554 is 45555518.

It can be written as a sum of positive squares in 2 ways, for example, as 56325025 + 25230529 = 7505^2 + 5023^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (81555557) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17339 + ... + 21534.

Almost surely, 2^81555554 is an apocalyptic number.

81555554 is a deficient number, since it is larger than the sum of its proper divisors (40897546).

81555554 is a wasteful number, since it uses less digits than its factorization.

81555554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39924.

The product of its digits is 100000, while the sum is 38.

The square root of 81555554 is about 9030.8113699711. The cubic root of 81555554 is about 433.6618126102.

The spelling of 81555554 in words is "eighty-one million, five hundred fifty-five thousand, five hundred fifty-four".