21290311 has 4 divisors (see below), whose sum is σ = 24331792. Its totient is φ = 18248832.

The previous prime is 21290303. The next prime is 21290323. The reversal of 21290311 is 11309212.

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

It is not a de Polignac number, because 21290311 - 2³ = 21290303 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21290351) 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, 1520730 + ... + 1520743.

It is an arithmetic number, because the mean of its divisors is an integer number (6082948).

Almost surely, 2^21290311 is an apocalyptic number.

21290311 is a deficient number, since it is larger than the sum of its proper divisors (3041481).

21290311 is an equidigital number, since it uses as much as digits as its factorization.

21290311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3041480.

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 21290311 is about 4614.1424988832. The cubic root of 21290311 is about 277.1579466477.

Adding to 21290311 its reverse (11309212), we get a palindrome (32599523).

The spelling of 21290311 in words is "twenty-one million, two hundred ninety thousand, three hundred eleven".