81982487 has 4 divisors (see below), whose sum is σ = 83020320. Its totient is φ = 80944656.

The previous prime is 81982477. The next prime is 81982499. The reversal of 81982487 is 78428918.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81982487 is a prime.

It is a super-2 number, since 2×81982487² = 13442256349410338, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81982427) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 518798 + ... + 518955.

It is an arithmetic number, because the mean of its divisors is an integer number (20755080).

Almost surely, 2^81982487 is an apocalyptic number.

81982487 is a deficient number, since it is larger than the sum of its proper divisors (1037833).

81982487 is a wasteful number, since it uses less digits than its factorization.

81982487 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1037832.

The product of its digits is 258048, while the sum is 47.

The square root of 81982487 is about 9054.4180928429. The cubic root of 81982487 is about 434.4172175519.

The spelling of 81982487 in words is "eighty-one million, nine hundred eighty-two thousand, four hundred eighty-seven".