197939921 has 4 divisors (see below), whose sum is σ = 198025572. Its totient is φ = 197854272.

The previous prime is 197939897. The next prime is 197939933. The reversal of 197939921 is 129939791.

197939921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 129939791 = 8387 ⋅15493.

It can be written as a sum of positive squares in 2 ways, for example, as 91107025 + 106832896 = 9545^2 + 10336^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-197939921 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 197939921.

It is not an unprimeable number, because it can be changed into a prime (197933921) 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, 39260 + ... + 44013.

It is an arithmetic number, because the mean of its divisors is an integer number (49506393).

Almost surely, 2^197939921 is an apocalyptic number.

It is an amenable number.

197939921 is a deficient number, since it is larger than the sum of its proper divisors (85651).

197939921 is an equidigital number, since it uses as much as digits as its factorization.

197939921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85650.

The product of its digits is 275562, while the sum is 50.

The square root of 197939921 is about 14069.1123031981. The cubic root of 197939921 is about 582.7887113430.

The spelling of 197939921 in words is "one hundred ninety-seven million, nine hundred thirty-nine thousand, nine hundred twenty-one".