81691150 has 12 divisors (see below), whose sum is σ = 151945632. Its totient is φ = 32676440.

The previous prime is 81691133. The next prime is 81691163. The reversal of 81691150 is 5119618.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 816862 + ... + 816961.

It is an arithmetic number, because the mean of its divisors is an integer number (12662136).

Almost surely, 2^81691150 is an apocalyptic number.

81691150 is a deficient number, since it is larger than the sum of its proper divisors (70254482).

81691150 is a wasteful number, since it uses less digits than its factorization.

81691150 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1633835 (or 1633830 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 31.

The square root of 81691150 is about 9038.3156616706. The cubic root of 81691150 is about 433.9020179892.

The spelling of 81691150 in words is "eighty-one million, six hundred ninety-one thousand, one hundred fifty".