81624461 has 2 divisors, whose sum is σ = 81624462. Its totient is φ = 81624460.

The previous prime is 81624443. The next prime is 81624509. The reversal of 81624461 is 16442618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50197225 + 31427236 = 7085^2 + 5606^2 .

It is a cyclic number.

It is not a de Polignac number, because 81624461 - 2²⁶ = 14515597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81624061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40812230 + 40812231.

It is an arithmetic number, because the mean of its divisors is an integer number (40812231).

Almost surely, 2^81624461 is an apocalyptic number.

It is an amenable number.

81624461 is a deficient number, since it is larger than the sum of its proper divisors (1).

81624461 is an equidigital number, since it uses as much as digits as its factorization.

81624461 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9216, while the sum is 32.

The square root of 81624461 is about 9034.6256701648. The cubic root of 81624461 is about 433.7839131133.

The spelling of 81624461 in words is "eighty-one million, six hundred twenty-four thousand, four hundred sixty-one".