81551155 has 16 divisors (see below), whose sum is σ = 112299264. Its totient is φ = 55692000.

The previous prime is 81551143. The next prime is 81551189. The reversal of 81551155 is 55115518.

It is a happy number.

It is not a de Polignac number, because 81551155 - 2⁷ = 81551027 is a prime.

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, 4144 + ... + 13426.

It is an arithmetic number, because the mean of its divisors is an integer number (7018704).

Almost surely, 2^81551155 is an apocalyptic number.

81551155 is a deficient number, since it is larger than the sum of its proper divisors (30748109).

81551155 is a wasteful number, since it uses less digits than its factorization.

81551155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9546.

The product of its digits is 5000, while the sum is 31.

The square root of 81551155 is about 9030.5678116052. The cubic root of 81551155 is about 433.6540154195.

The spelling of 81551155 in words is "eighty-one million, five hundred fifty-one thousand, one hundred fifty-five".