81921467 has 2 divisors, whose sum is σ = 81921468. Its totient is φ = 81921466.

The previous prime is 81921439. The next prime is 81921509. The reversal of 81921467 is 76412918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81921467 - 2⁸ = 81921211 is a prime.

It is a super-2 number, since 2×81921467² = 13422253510864178, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81921467.

It is not a weakly prime, because it can be changed into another prime (81921067) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40960733 + 40960734.

It is an arithmetic number, because the mean of its divisors is an integer number (40960734).

Almost surely, 2^81921467 is an apocalyptic number.

81921467 is a deficient number, since it is larger than the sum of its proper divisors (1).

81921467 is an equidigital number, since it uses as much as digits as its factorization.

81921467 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192, while the sum is 38.

The square root of 81921467 is about 9051.0478398912. The cubic root of 81921467 is about 434.3094111206.

The spelling of 81921467 in words is "eighty-one million, nine hundred twenty-one thousand, four hundred sixty-seven".