81691350 has 48 divisors (see below), whose sum is σ = 218183952. Its totient is φ = 20108160.

The previous prime is 81691343. The next prime is 81691361. The reversal of 81691350 is 5319618.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18997 + ... + 22896.

It is an arithmetic number, because the mean of its divisors is an integer number (4545499).

Almost surely, 2^81691350 is an apocalyptic number.

81691350 is an abundant number, since it is smaller than the sum of its proper divisors (136492602).

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

81691350 is a wasteful number, since it uses less digits than its factorization.

81691350 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41921 (or 41916 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 33.

The square root of 81691350 is about 9038.3267256722. The cubic root of 81691350 is about 433.9023720885.

The spelling of 81691350 in words is "eighty-one million, six hundred ninety-one thousand, three hundred fifty".