21740291 has 4 divisors (see below), whose sum is σ = 22270584. Its totient is φ = 21210000.

The previous prime is 21740287. The next prime is 21740309. The reversal of 21740291 is 19204712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21740291 - 2² = 21740287 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21740291.

It is not an unprimeable number, because it can be changed into a prime (21740231) 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 3 ways as a sum of consecutive naturals, for example, 265085 + ... + 265166.

It is an arithmetic number, because the mean of its divisors is an integer number (5567646).

Almost surely, 2^21740291 is an apocalyptic number.

21740291 is a deficient number, since it is larger than the sum of its proper divisors (530293).

21740291 is an equidigital number, since it uses as much as digits as its factorization.

21740291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 530292.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 21740291 is about 4662.6484962948. The cubic root of 21740291 is about 279.0969674466.

The spelling of 21740291 in words is "twenty-one million, seven hundred forty thousand, two hundred ninety-one".