997000721 has 4 divisors (see below), whose sum is σ = 997387812. Its totient is φ = 996613632.

The previous prime is 997000691. The next prime is 997000723. The reversal of 997000721 is 127000799.

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

It can be written as a sum of positive squares in 2 ways, for example, as 804346321 + 192654400 = 28361^2 + 13880^2 .

It is a cyclic number.

It is not a de Polignac number, because 997000721 - 2²² = 992806417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (997000723) 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, 189656 + ... + 194841.

It is an arithmetic number, because the mean of its divisors is an integer number (249346953).

Almost surely, 2^997000721 is an apocalyptic number.

It is an amenable number.

997000721 is a deficient number, since it is larger than the sum of its proper divisors (387091).

997000721 is a wasteful number, since it uses less digits than its factorization.

997000721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 387090.

The product of its (nonzero) digits is 7938, while the sum is 35.

The square root of 997000721 is about 31575.3182248414. The cubic root of 997000721 is about 998.9992391451. Note that the first 3 decimals are identical.

The spelling of 997000721 in words is "nine hundred ninety-seven million, seven hundred twenty-one", and thus it is an aban number.