81531154 has 4 divisors (see below), whose sum is σ = 122296734. Its totient is φ = 40765576.

The previous prime is 81531143. The next prime is 81531169. The reversal of 81531154 is 45113518.

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., 80371225 + 1159929 = 8965^2 + 1077^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20382787 + ... + 20382790.

Almost surely, 2^81531154 is an apocalyptic number.

81531154 is a deficient number, since it is larger than the sum of its proper divisors (40765580).

81531154 is a wasteful number, since it uses less digits than its factorization.

81531154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40765579.

The product of its digits is 2400, while the sum is 28.

The square root of 81531154 is about 9029.4603382483. The cubic root of 81531154 is about 433.6185602783.

The spelling of 81531154 in words is "eighty-one million, five hundred thirty-one thousand, one hundred fifty-four".