81321619 has 2 divisors, whose sum is σ = 81321620. Its totient is φ = 81321618.

The previous prime is 81321593. The next prime is 81321637. The reversal of 81321619 is 91612318.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81321619 - 2¹⁹ = 80797331 is a prime.

It is a super-2 number, since 2×81321619² = 13226411433562322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81321679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40660809 + 40660810.

It is an arithmetic number, because the mean of its divisors is an integer number (40660810).

Almost surely, 2^81321619 is an apocalyptic number.

81321619 is a deficient number, since it is larger than the sum of its proper divisors (1).

81321619 is an equidigital number, since it uses as much as digits as its factorization.

81321619 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 31.

The square root of 81321619 is about 9017.8500209307. The cubic root of 81321619 is about 433.2467751504.

The spelling of 81321619 in words is "eighty-one million, three hundred twenty-one thousand, six hundred nineteen".