21451311 has 24 divisors (see below), whose sum is σ = 36726144. Its totient is φ = 12256920.

The previous prime is 21451307. The next prime is 21451319. The reversal of 21451311 is 11315412.

It is not a de Polignac number, because 21451311 - 2² = 21451307 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21451319) 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 23 ways as a sum of consecutive naturals, for example, 4605 + ... + 8006.

It is an arithmetic number, because the mean of its divisors is an integer number (1530256).

Almost surely, 2^21451311 is an apocalyptic number.

21451311 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21451311 is a deficient number, since it is larger than the sum of its proper divisors (15274833).

21451311 is an equidigital number, since it uses as much as digits as its factorization.

21451311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12633 (or 12621 counting only the distinct ones).

The product of its digits is 120, while the sum is 18.

The square root of 21451311 is about 4631.5560020365. The cubic root of 21451311 is about 277.8548273313.

Adding to 21451311 its reverse (11315412), we get a palindrome (32766723).

The spelling of 21451311 in words is "twenty-one million, four hundred fifty-one thousand, three hundred eleven".