187961367221 has 4 divisors (see below), whose sum is σ = 199017918252. Its totient is φ = 176904816192.

The previous prime is 187961367193. The next prime is 187961367263. The reversal of 187961367221 is 122763169781.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 175465480996 + 12495886225 = 418886^2 + 111785^2 .

It is a cyclic number.

It is not a de Polignac number, because 187961367221 - 2²² = 187957172917 is a prime.

It is a super-2 number, since 2×187961367221² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (187961367421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5528275490 + ... + 5528275523.

It is an arithmetic number, because the mean of its divisors is an integer number (49754479563).

Almost surely, 2^187961367221 is an apocalyptic number.

It is an amenable number.

187961367221 is a deficient number, since it is larger than the sum of its proper divisors (11056551031).

187961367221 is a wasteful number, since it uses less digits than its factorization.

187961367221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11056551030.

The product of its digits is 1524096, while the sum is 53.

The spelling of 187961367221 in words is "one hundred eighty-seven billion, nine hundred sixty-one million, three hundred sixty-seven thousand, two hundred twenty-one".