81257249 has 8 divisors (see below), whose sum is σ = 83368992. Its totient is φ = 79172640.

The previous prime is 81257237. The next prime is 81257251. The reversal of 81257249 is 94275218.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81257249 - 2²⁴ = 64480033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81257149) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 647 + ... + 12764.

It is an arithmetic number, because the mean of its divisors is an integer number (10421124).

Almost surely, 2^81257249 is an apocalyptic number.

It is an amenable number.

81257249 is a deficient number, since it is larger than the sum of its proper divisors (2111743).

81257249 is a wasteful number, since it uses less digits than its factorization.

81257249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13567.

The product of its digits is 40320, while the sum is 38.

The square root of 81257249 is about 9014.2802818639. The cubic root of 81257249 is about 433.1324330408.

The spelling of 81257249 in words is "eighty-one million, two hundred fifty-seven thousand, two hundred forty-nine".