81980399 has 8 divisors (see below), whose sum is σ = 84739200. Its totient is φ = 79228800.

The previous prime is 81980377. The next prime is 81980407. The reversal of 81980399 is 99308918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81980399 - 2¹² = 81976303 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81980309) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31259 + ... + 33779.

It is an arithmetic number, because the mean of its divisors is an integer number (10592400).

Almost surely, 2^81980399 is an apocalyptic number.

81980399 is a deficient number, since it is larger than the sum of its proper divisors (2758801).

81980399 is a wasteful number, since it uses less digits than its factorization.

81980399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3601.

The product of its (nonzero) digits is 139968, while the sum is 47.

The square root of 81980399 is about 9054.3027892820. The cubic root of 81980399 is about 434.4135294843.

It can be divided in two parts, 819 and 80399, that added together give a palindrome (81218).

The spelling of 81980399 in words is "eighty-one million, nine hundred eighty thousand, three hundred ninety-nine".