81661152 has 24 divisors (see below), whose sum is σ = 214360776. Its totient is φ = 27220352.

The previous prime is 81661123. The next prime is 81661159. The reversal of 81661152 is 25116618.

It is a tau number, because it is divible by the number of its divisors (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81661159) 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, 425223 + ... + 425414.

It is an arithmetic number, because the mean of its divisors is an integer number (8931699).

Almost surely, 2^81661152 is an apocalyptic number.

It is an amenable number.

81661152 is an abundant number, since it is smaller than the sum of its proper divisors (132699624).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81661152 is a wasteful number, since it uses less digits than its factorization.

81661152 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 850650 (or 850642 counting only the distinct ones).

The product of its digits is 2880, while the sum is 30.

The square root of 81661152 is about 9036.6560186830. The cubic root of 81661152 is about 433.8489000921.

The spelling of 81661152 in words is "eighty-one million, six hundred sixty-one thousand, one hundred fifty-two".