187923993421 has 4 divisors (see below), whose sum is σ = 188050203100. Its totient is φ = 187797783744.

The previous prime is 187923993409. The next prime is 187923993461. The reversal of 187923993421 is 124399329781.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 124399329781 = 339617 ⋅366293.

It can be written as a sum of positive squares in 2 ways, for example, as 12857065321 + 175066928100 = 113389^2 + 418410^2 .

It is a cyclic number.

It is not a de Polignac number, because 187923993421 - 2⁹ = 187923992909 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 (187923993461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63102606 + ... + 63105583.

It is an arithmetic number, because the mean of its divisors is an integer number (47012550775).

Almost surely, 2^187923993421 is an apocalyptic number.

It is an amenable number.

187923993421 is a deficient number, since it is larger than the sum of its proper divisors (126209679).

187923993421 is a wasteful number, since it uses less digits than its factorization.

187923993421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126209678.

The product of its digits is 5878656, while the sum is 58.

The spelling of 187923993421 in words is "one hundred eighty-seven billion, nine hundred twenty-three million, nine hundred ninety-three thousand, four hundred twenty-one".