195557921 has 4 divisors (see below), whose sum is σ = 210600852. Its totient is φ = 180514992.

The previous prime is 195557893. The next prime is 195557941. The reversal of 195557921 is 129755591.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 129755591 = 7 ⋅18536513.

It can be written as a sum of positive squares in 2 ways, for example, as 18800896 + 176757025 = 4336^2 + 13295^2 .

It is a cyclic number.

It is not a de Polignac number, because 195557921 - 2¹⁸ = 195295777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (195557941) 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, 7521446 + ... + 7521471.

It is an arithmetic number, because the mean of its divisors is an integer number (52650213).

Almost surely, 2^195557921 is an apocalyptic number.

It is an amenable number.

195557921 is a deficient number, since it is larger than the sum of its proper divisors (15042931).

195557921 is a wasteful number, since it uses less digits than its factorization.

195557921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15042930.

The product of its digits is 141750, while the sum is 44.

The square root of 195557921 is about 13984.2025514507. The cubic root of 195557921 is about 580.4415197373.

The spelling of 195557921 in words is "one hundred ninety-five million, five hundred fifty-seven thousand, nine hundred twenty-one".