81961279 has 8 divisors (see below), whose sum is σ = 86592960. Its totient is φ = 77450016.

The previous prime is 81961277. The next prime is 81961309. The reversal of 81961279 is 97216918.

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 81961279 - 2¹ = 81961277 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 (81961277) 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, 28704 + ... + 31429.

It is an arithmetic number, because the mean of its divisors is an integer number (10824120).

Almost surely, 2^81961279 is an apocalyptic number.

81961279 is a deficient number, since it is larger than the sum of its proper divisors (4631681).

81961279 is a wasteful number, since it uses less digits than its factorization.

81961279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60209.

The product of its digits is 54432, while the sum is 43.

The square root of 81961279 is about 9053.2468761213. The cubic root of 81961279 is about 434.3797546121.

The spelling of 81961279 in words is "eighty-one million, nine hundred sixty-one thousand, two hundred seventy-nine".