81621467 has 2 divisors, whose sum is σ = 81621468. Its totient is φ = 81621466.

The previous prime is 81621461. The next prime is 81621479. The reversal of 81621467 is 76412618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81621467 - 2⁴ = 81621451 is a prime.

It is equal to p_4758632 and since 81621467 and 4758632 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (81621461) 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, 40810733 + 40810734.

It is an arithmetic number, because the mean of its divisors is an integer number (40810734).

Almost surely, 2^81621467 is an apocalyptic number.

81621467 is a deficient number, since it is larger than the sum of its proper divisors (1).

81621467 is an equidigital number, since it uses as much as digits as its factorization.

81621467 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16128, while the sum is 35.

The square root of 81621467 is about 9034.4599727931. The cubic root of 81621467 is about 433.7786092910.

The spelling of 81621467 in words is "eighty-one million, six hundred twenty-one thousand, four hundred sixty-seven".