198880021 has 4 divisors (see below), whose sum is σ = 199018912. Its totient is φ = 198741132.

The previous prime is 198880013. The next prime is 198880037. The reversal of 198880021 is 120088891.

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.

It is a cyclic number.

It is not a de Polignac number, because 198880021 - 2³ = 198880013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (198880061) 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, 67275 + ... + 70168.

It is an arithmetic number, because the mean of its divisors is an integer number (49754728).

Almost surely, 2^198880021 is an apocalyptic number.

It is an amenable number.

198880021 is a deficient number, since it is larger than the sum of its proper divisors (138891).

198880021 is a wasteful number, since it uses less digits than its factorization.

198880021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138890.

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 198880021 is about 14102.4827955931. The cubic root of 198880021 is about 583.7098908197.

The spelling of 198880021 in words is "one hundred ninety-eight million, eight hundred eighty thousand, twenty-one".