81399357 has 24 divisors (see below), whose sum is σ = 130588800. Its totient is φ = 50089104.

The previous prime is 81399313. The next prime is 81399377. The reversal of 81399357 is 75399318.

It is a happy number.

It is not a de Polignac number, because 81399357 - 2⁶ = 81399293 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81399377) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4357 + ... + 13482.

It is an arithmetic number, because the mean of its divisors is an integer number (5441200).

Almost surely, 2^81399357 is an apocalyptic number.

It is an amenable number.

81399357 is a deficient number, since it is larger than the sum of its proper divisors (49189443).

81399357 is a wasteful number, since it uses less digits than its factorization.

81399357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17874 (or 17855 counting only the distinct ones).

The product of its digits is 204120, while the sum is 45.

The square root of 81399357 is about 9022.1592204971. The cubic root of 81399357 is about 433.3847827801.

The spelling of 81399357 in words is "eighty-one million, three hundred ninety-nine thousand, three hundred fifty-seven".