21211451 has 4 divisors (see below), whose sum is σ = 22133712. Its totient is φ = 20289192.

The previous prime is 21211433. The next prime is 21211481. The reversal of 21211451 is 15411212.

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 21211451 - 2⁶ = 21211387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21211481) 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, 461096 + ... + 461141.

It is an arithmetic number, because the mean of its divisors is an integer number (5533428).

Almost surely, 2^21211451 is an apocalyptic number.

21211451 is a deficient number, since it is larger than the sum of its proper divisors (922261).

21211451 is an equidigital number, since it uses as much as digits as its factorization.

21211451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 922260.

The product of its digits is 80, while the sum is 17.

The square root of 21211451 is about 4605.5891045555. The cubic root of 21211451 is about 276.8153226048.

Adding to 21211451 its reverse (15411212), we get a palindrome (36622663).

The spelling of 21211451 in words is "twenty-one million, two hundred eleven thousand, four hundred fifty-one".