188912921 has 4 divisors (see below), whose sum is σ = 189143844. Its totient is φ = 188682000.

The previous prime is 188912909. The next prime is 188912957. The reversal of 188912921 is 129219881.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 129219881 = 7 ⋅18459983.

It can be written as a sum of positive squares in 2 ways, for example, as 45751696 + 143161225 = 6764^2 + 11965^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-188912921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (188912981) 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, 114230 + ... + 115871.

It is an arithmetic number, because the mean of its divisors is an integer number (47285961).

Almost surely, 2^188912921 is an apocalyptic number.

It is an amenable number.

188912921 is a deficient number, since it is larger than the sum of its proper divisors (230923).

188912921 is an equidigital number, since it uses as much as digits as its factorization.

188912921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230922.

The product of its digits is 20736, while the sum is 41.

The square root of 188912921 is about 13744.5596873818. The cubic root of 188912921 is about 573.7912057717.

It can be divided in two parts, 18891 and 2921, that added together give a palindrome (21812).

The spelling of 188912921 in words is "one hundred eighty-eight million, nine hundred twelve thousand, nine hundred twenty-one".