997305721 has 4 divisors (see below), whose sum is σ = 997408512. Its totient is φ = 997202932.

The previous prime is 997305709. The next prime is 997305761. The reversal of 997305721 is 127503799.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 997305721 - 2¹³ = 997297529 is a prime.

It is a super-2 number, since 2×997305721² = 1989237402278659682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (997305761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35125 + ... + 56818.

It is an arithmetic number, because the mean of its divisors is an integer number (249352128).

Almost surely, 2^997305721 is an apocalyptic number.

It is an amenable number.

997305721 is a deficient number, since it is larger than the sum of its proper divisors (102791).

997305721 is a wasteful number, since it uses less digits than its factorization.

997305721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102790.

The product of its (nonzero) digits is 119070, while the sum is 43.

The square root of 997305721 is about 31580.1475772359. The cubic root of 997305721 is about 999.1010992195.

The spelling of 997305721 in words is "nine hundred ninety-seven million, three hundred five thousand, seven hundred twenty-one".