1891274521 has 4 divisors (see below), whose sum is σ = 1973503872. Its totient is φ = 1809045172.

The previous prime is 1891274513. The next prime is 1891274533. The reversal of 1891274521 is 1254721981.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1891274521 - 2³ = 1891274513 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1891274921) 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, 41114641 + ... + 41114686.

It is an arithmetic number, because the mean of its divisors is an integer number (493375968).

Almost surely, 2^1891274521 is an apocalyptic number.

It is an amenable number.

1891274521 is a deficient number, since it is larger than the sum of its proper divisors (82229351).

1891274521 is an equidigital number, since it uses as much as digits as its factorization.

1891274521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82229350.

The product of its digits is 40320, while the sum is 40.

The square root of 1891274521 is about 43488.7861522945. The cubic root of 1891274521 is about 1236.6634462596.

The spelling of 1891274521 in words is "one billion, eight hundred ninety-one million, two hundred seventy-four thousand, five hundred twenty-one".