21290349 has 4 divisors (see below), whose sum is σ = 28387136. Its totient is φ = 14193564.

The previous prime is 21290323. The next prime is 21290351. The reversal of 21290349 is 94309212.

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 not a de Polignac number, because 21290349 - 2¹⁵ = 21257581 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21290449) 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, 3548389 + ... + 3548394.

It is an arithmetic number, because the mean of its divisors is an integer number (7096784).

Almost surely, 2^21290349 is an apocalyptic number.

It is an amenable number.

21290349 is a deficient number, since it is larger than the sum of its proper divisors (7096787).

21290349 is an equidigital number, since it uses as much as digits as its factorization.

21290349 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7096786.

The product of its (nonzero) digits is 3888, while the sum is 30.

The square root of 21290349 is about 4614.1466166562. The cubic root of 21290349 is about 277.1581115426.

The spelling of 21290349 in words is "twenty-one million, two hundred ninety thousand, three hundred forty-nine".