191030921 has 16 divisors (see below), whose sum is σ = 216950400. Its totient is φ = 167102208.

The previous prime is 191030909. The next prime is 191030929. The reversal of 191030921 is 129030191.

191030921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 191030921 - 2¹⁰ = 191029897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (191030929) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11540 + ... + 22698.

It is an arithmetic number, because the mean of its divisors is an integer number (13559400).

Almost surely, 2^191030921 is an apocalyptic number.

It is an amenable number.

191030921 is a deficient number, since it is larger than the sum of its proper divisors (25919479).

191030921 is a wasteful number, since it uses less digits than its factorization.

191030921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11248.

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 191030921 is about 13821.3935983315. The cubic root of 191030921 is about 575.9275976784.

The spelling of 191030921 in words is "one hundred ninety-one million, thirty thousand, nine hundred twenty-one".