81383251 has 16 divisors (see below), whose sum is σ = 89395200. Its totient is φ = 73791648.

The previous prime is 81383231. The next prime is 81383257. The reversal of 81383251 is 15238318.

It is a cyclic number.

It is not a de Polignac number, because 81383251 - 2⁹ = 81382739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81383257) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69396 + ... + 70558.

It is an arithmetic number, because the mean of its divisors is an integer number (5587200).

Almost surely, 2^81383251 is an apocalyptic number.

81383251 is the 7366-th pentagonal number.

81383251 is a deficient number, since it is larger than the sum of its proper divisors (8011949).

81383251 is a wasteful number, since it uses less digits than its factorization.

81383251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1338.

The product of its digits is 5760, while the sum is 31.

The square root of 81383251 is about 9021.2665962159. The cubic root of 81383251 is about 433.3561971500.

The spelling of 81383251 in words is "eighty-one million, three hundred eighty-three thousand, two hundred fifty-one".