198878639 has 2 divisors, whose sum is σ = 198878640. Its totient is φ = 198878638.

The previous prime is 198878527. The next prime is 198878657. The reversal of 198878639 is 936878891.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 198878639 - 2²⁰ = 197830063 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (198878689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99439319 + 99439320.

It is an arithmetic number, because the mean of its divisors is an integer number (99439320).

Almost surely, 2^198878639 is an apocalyptic number.

198878639 is a deficient number, since it is larger than the sum of its proper divisors (1).

198878639 is an equidigital number, since it uses as much as digits as its factorization.

198878639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5225472, while the sum is 59.

The square root of 198878639 is about 14102.4337970437. The cubic root of 198878639 is about 583.7085387668.

The spelling of 198878639 in words is "one hundred ninety-eight million, eight hundred seventy-eight thousand, six hundred thirty-nine".