81572279 has 8 divisors (see below), whose sum is σ = 83106000. Its totient is φ = 80043712.

The previous prime is 81572243. The next prime is 81572287. The reversal of 81572279 is 97227518.

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 81572279 - 2¹² = 81568183 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 (81572219) 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, 46877 + ... + 48585.

It is an arithmetic number, because the mean of its divisors is an integer number (10388250).

Almost surely, 2^81572279 is an apocalyptic number.

81572279 is a deficient number, since it is larger than the sum of its proper divisors (1533721).

81572279 is a wasteful number, since it uses less digits than its factorization.

81572279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2577.

The product of its digits is 70560, while the sum is 41.

The square root of 81572279 is about 9031.7373190323. The cubic root of 81572279 is about 433.6914549734.

The spelling of 81572279 in words is "eighty-one million, five hundred seventy-two thousand, two hundred seventy-nine".