81951457 has 8 divisors (see below), whose sum is σ = 93912896. Its totient is φ = 70053552.

The previous prime is 81951451. The next prime is 81951473. The reversal of 81951457 is 75415918.

It is a happy number.

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 81951457 - 2¹⁹ = 81427169 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81951451) 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, 13083 + ... + 18304.

It is an arithmetic number, because the mean of its divisors is an integer number (11739112).

Almost surely, 2^81951457 is an apocalyptic number.

It is an amenable number.

81951457 is a deficient number, since it is larger than the sum of its proper divisors (11961439).

81951457 is a wasteful number, since it uses less digits than its factorization.

81951457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31767.

The product of its digits is 50400, while the sum is 40.

The square root of 81951457 is about 9052.7044025529. The cubic root of 81951457 is about 434.3624023191.

The spelling of 81951457 in words is "eighty-one million, nine hundred fifty-one thousand, four hundred fifty-seven".