81555532 has 6 divisors (see below), whose sum is σ = 142722188. Its totient is φ = 40777764.

The previous prime is 81555517. The next prime is 81555533. The reversal of 81555532 is 23555518.

It is not an unprimeable number, because it can be changed into a prime (81555533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10194438 + ... + 10194445.

Almost surely, 2^81555532 is an apocalyptic number.

It is an amenable number.

81555532 is a deficient number, since it is larger than the sum of its proper divisors (61166656).

81555532 is a wasteful number, since it uses less digits than its factorization.

81555532 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20388887 (or 20388885 counting only the distinct ones).

The product of its digits is 30000, while the sum is 34.

The square root of 81555532 is about 9030.8101519188. The cubic root of 81555532 is about 433.6617736161.

The spelling of 81555532 in words is "eighty-one million, five hundred fifty-five thousand, five hundred thirty-two".