997581 has 8 divisors (see below), whose sum is σ = 1432480. Its totient is φ = 613872.

The previous prime is 997573. The next prime is 997583. The reversal of 997581 is 185799.

It is a happy number.

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

It is not a de Polignac number, because 997581 - 2³ = 997573 is a prime.

It is a super-2 number, since 2×997581² = 1990335703122, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39), and also a Moran number because the ratio is a prime number: 25579 = 997581 / (9 + 9 + 7 + 5 + 8 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (997583) 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, 12751 + ... + 12828.

It is an arithmetic number, because the mean of its divisors is an integer number (179060).

2⁹⁹⁷⁵⁸¹ is an apocalyptic number.

It is an amenable number.

997581 is a deficient number, since it is larger than the sum of its proper divisors (434899).

997581 is a wasteful number, since it uses less digits than its factorization.

997581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25595.

The product of its digits is 22680, while the sum is 39.

The square root of 997581 is about 998.7897676689. The cubic root of 997581 is about 99.9193015618.

The spelling of 997581 in words is "nine hundred ninety-seven thousand, five hundred eighty-one".