81619169 has 2 divisors, whose sum is σ = 81619170. Its totient is φ = 81619168.

The previous prime is 81619163. The next prime is 81619189. The reversal of 81619169 is 96191618.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 70140625 + 11478544 = 8375^2 + 3388^2 .

It is a cyclic number.

It is not a de Polignac number, because 81619169 - 2¹² = 81615073 is a prime.

It is a super-2 number, since 2×81619169² = 13323377496501122, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81619163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40809584 + 40809585.

It is an arithmetic number, because the mean of its divisors is an integer number (40809585).

Almost surely, 2^81619169 is an apocalyptic number.

It is an amenable number.

81619169 is a deficient number, since it is larger than the sum of its proper divisors (1).

81619169 is an equidigital number, since it uses as much as digits as its factorization.

81619169 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23328, while the sum is 41.

The square root of 81619169 is about 9034.3327921878. The cubic root of 81619169 is about 433.7745383333.

The spelling of 81619169 in words is "eighty-one million, six hundred nineteen thousand, one hundred sixty-nine".