81309487 has 8 divisors (see below), whose sum is σ = 98391456. Its totient is φ = 65594112.

The previous prime is 81309469. The next prime is 81309499. The reversal of 81309487 is 78490318.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81309487 is a prime.

It is a super-2 number, since 2×81309487² = 13222465352406338, 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 (81309467) 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, 341518 + ... + 341755.

It is an arithmetic number, because the mean of its divisors is an integer number (12298932).

Almost surely, 2^81309487 is an apocalyptic number.

81309487 is a deficient number, since it is larger than the sum of its proper divisors (17081969).

81309487 is a wasteful number, since it uses less digits than its factorization.

81309487 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 683297.

The product of its (nonzero) digits is 48384, while the sum is 40.

The square root of 81309487 is about 9017.1773299631. The cubic root of 81309487 is about 433.2252293780.

It can be divided in two parts, 81309 and 487, that added together give a square (81796 = 286²).

The spelling of 81309487 in words is "eighty-one million, three hundred nine thousand, four hundred eighty-seven".