21490311 has 16 divisors (see below), whose sum is σ = 30343040. Its totient is φ = 13491360.

The previous prime is 21490309. The next prime is 21490319. The reversal of 21490311 is 11309412.

It is not a de Polignac number, because 21490311 - 2¹ = 21490309 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 (21490319) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9276 + ... + 11358.

It is an arithmetic number, because the mean of its divisors is an integer number (1896440).

Almost surely, 2^21490311 is an apocalyptic number.

21490311 is a deficient number, since it is larger than the sum of its proper divisors (8852729).

21490311 is a wasteful number, since it uses less digits than its factorization.

21490311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2286.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 21490311 is about 4635.7643382726. The cubic root of 21490311 is about 278.0231119615.

Adding to 21490311 its reverse (11309412), we get a palindrome (32799723).

It can be divided in two parts, 214 and 90311, that added together give a triangular number (90525 = T₄₂₅).

The spelling of 21490311 in words is "twenty-one million, four hundred ninety thousand, three hundred eleven".