81624490 has 12 divisors (see below), whose sum is σ = 146975526. Its totient is φ = 32638368.

The previous prime is 81624461. The next prime is 81624509. The reversal of 81624490 is 9442618.

It can be written as a sum of positive squares in 3 ways, for example, as 75116889 + 6507601 = 8667^2 + 2551^2 .

It is an unprimeable number.

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 in 5 ways as a sum of consecutive naturals, for example, 27142 + ... + 29998.

Almost surely, 2^81624490 is an apocalyptic number.

81624490 is a deficient number, since it is larger than the sum of its proper divisors (65351036).

81624490 is an frugal number, since it uses more digits than its factorization.

81624490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5721 (or 2864 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 34.

The square root of 81624490 is about 9034.6272751011. The cubic root of 81624490 is about 433.7839644857.

The spelling of 81624490 in words is "eighty-one million, six hundred twenty-four thousand, four hundred ninety".