191260021 has 4 divisors (see below), whose sum is σ = 193409100. Its totient is φ = 189110944.

The previous prime is 191259983. The next prime is 191260031. The reversal of 191260021 is 120062191.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120062191 = 67 ⋅1791973.

It can be written as a sum of positive squares in 2 ways, for example, as 57972996 + 133287025 = 7614^2 + 11545^2 .

It is a cyclic number.

It is not a de Polignac number, because 191260021 - 2¹³ = 191251829 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 191259974 and 191260001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191260031) 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, 1074406 + ... + 1074583.

It is an arithmetic number, because the mean of its divisors is an integer number (48352275).

Almost surely, 2^191260021 is an apocalyptic number.

It is an amenable number.

191260021 is a deficient number, since it is larger than the sum of its proper divisors (2149079).

191260021 is an equidigital number, since it uses as much as digits as its factorization.

191260021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2149078.

The product of its (nonzero) digits is 216, while the sum is 22.

The square root of 191260021 is about 13829.6789912131. The cubic root of 191260021 is about 576.1577389571.

The spelling of 191260021 in words is "one hundred ninety-one million, two hundred sixty thousand, twenty-one".