81617479 has 2 divisors, whose sum is σ = 81617480. Its totient is φ = 81617478.

The previous prime is 81617477. The next prime is 81617491. The reversal of 81617479 is 97471618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81617479 - 2¹ = 81617477 is a prime.

It is a super-2 number, since 2×81617479² = 13322825756630882, which contains 22 as substring.

Together with 81617477, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81617477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40808739 + 40808740.

It is an arithmetic number, because the mean of its divisors is an integer number (40808740).

Almost surely, 2^81617479 is an apocalyptic number.

81617479 is a deficient number, since it is larger than the sum of its proper divisors (1).

81617479 is an equidigital number, since it uses as much as digits as its factorization.

81617479 is an evil number, because the sum of its binary digits is even.

The product of its digits is 84672, while the sum is 43.

The square root of 81617479 is about 9034.2392596167. The cubic root of 81617479 is about 433.7715444123.

The spelling of 81617479 in words is "eighty-one million, six hundred seventeen thousand, four hundred seventy-nine".