81256237 has 4 divisors (see below), whose sum is σ = 81276480. Its totient is φ = 81235996.

The previous prime is 81256229. The next prime is 81256247. The reversal of 81256237 is 73265218.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81256237 - 2³ = 81256229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81256247) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1843 + ... + 12880.

It is an arithmetic number, because the mean of its divisors is an integer number (20319120).

Almost surely, 2^81256237 is an apocalyptic number.

It is an amenable number.

81256237 is a deficient number, since it is larger than the sum of its proper divisors (20243).

81256237 is a wasteful number, since it uses less digits than its factorization.

81256237 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20242.

The product of its digits is 20160, while the sum is 34.

The square root of 81256237 is about 9014.2241485333. The cubic root of 81256237 is about 433.1306349167.

The spelling of 81256237 in words is "eighty-one million, two hundred fifty-six thousand, two hundred thirty-seven".