81001986 has 16 divisors (see below), whose sum is σ = 174465984. Its totient is φ = 24923664.

The previous prime is 81001979. The next prime is 81001993. The reversal of 81001986 is 68910018.

It is an interprime number because it is at equal distance from previous prime (81001979) and next prime (81001993).

It is a super-2 number, since 2×81001986² = 13122643471888392, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 519166 + ... + 519321.

It is an arithmetic number, because the mean of its divisors is an integer number (10904124).

Almost surely, 2^81001986 is an apocalyptic number.

81001986 is an abundant number, since it is smaller than the sum of its proper divisors (93463998).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81001986 is a wasteful number, since it uses less digits than its factorization.

81001986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1038505.

The product of its (nonzero) digits is 3456, while the sum is 33.

The square root of 81001986 is about 9000.1103326570. The cubic root of 81001986 is about 432.6784072456.

The spelling of 81001986 in words is "eighty-one million, one thousand, nine hundred eighty-six".