81342257 has 4 divisors (see below), whose sum is σ = 81588336. Its totient is φ = 81096180.

The previous prime is 81342253. The next prime is 81342277. The reversal of 81342257 is 75224318.

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 81342257 - 2² = 81342253 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81342253) 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, 122543 + ... + 123204.

It is an arithmetic number, because the mean of its divisors is an integer number (20397084).

Almost surely, 2^81342257 is an apocalyptic number.

It is an amenable number.

81342257 is a deficient number, since it is larger than the sum of its proper divisors (246079).

81342257 is a wasteful number, since it uses less digits than its factorization.

81342257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246078.

The product of its digits is 13440, while the sum is 32.

The square root of 81342257 is about 9018.9942343922. The cubic root of 81342257 is about 433.2834221936.

The spelling of 81342257 in words is "eighty-one million, three hundred forty-two thousand, two hundred fifty-seven".