191439021 has 8 divisors (see below), whose sum is σ = 260068320. Its totient is φ = 125217872.

The previous prime is 191439013. The next prime is 191439047. The reversal of 191439021 is 120934191.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 191439021 - 2³ = 191439013 is a prime.

It is a super-2 number, since 2×191439021² = 73297797522876882, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 191439021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191439821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 601851 + ... + 602168.

It is an arithmetic number, because the mean of its divisors is an integer number (32508540).

Almost surely, 2^191439021 is an apocalyptic number.

It is an amenable number.

191439021 is a deficient number, since it is larger than the sum of its proper divisors (68629299).

191439021 is a wasteful number, since it uses less digits than its factorization.

191439021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1204075.

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 191439021 is about 13836.1490668466. The cubic root of 191439021 is about 576.3374246675.

The spelling of 191439021 in words is "one hundred ninety-one million, four hundred thirty-nine thousand, twenty-one".