997658921 has 16 divisors (see below), whose sum is σ = 1155840000. Its totient is φ = 843427728.

The previous prime is 997658903. The next prime is 997658929. The reversal of 997658921 is 129856799.

It is a cyclic number.

It is not a de Polignac number, because 997658921 - 2¹⁴ = 997642537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (997658929) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 498080 + ... + 500078.

It is an arithmetic number, because the mean of its divisors is an integer number (72240000).

Almost surely, 2^997658921 is an apocalyptic number.

It is an amenable number.

997658921 is a deficient number, since it is larger than the sum of its proper divisors (158181079).

997658921 is a wasteful number, since it uses less digits than its factorization.

997658921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2948.

The product of its digits is 2449440, while the sum is 56.

The square root of 997658921 is about 31585.7392030011. The cubic root of 997658921 is about 999.2190305789.

The spelling of 997658921 in words is "nine hundred ninety-seven million, six hundred fifty-eight thousand, nine hundred twenty-one".