81000947 has 8 divisors (see below), whose sum is σ = 82134000. Its totient is φ = 79873024.

The previous prime is 81000929. The next prime is 81000961. The reversal of 81000947 is 74900018.

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 81000947 - 2²⁶ = 13892083 is a prime.

It is a super-2 number, since 2×81000947² = 13122306829793618, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81000047) 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, 38948 + ... + 40974.

It is an arithmetic number, because the mean of its divisors is an integer number (10266750).

Almost surely, 2^81000947 is an apocalyptic number.

81000947 is a deficient number, since it is larger than the sum of its proper divisors (1133053).

81000947 is a wasteful number, since it uses less digits than its factorization.

81000947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2565.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 81000947 is about 9000.0526109573. The cubic root of 81000947 is about 432.6765572713.

The spelling of 81000947 in words is "eighty-one million, nine hundred forty-seven", and thus it is an aban number.