21354451 has 2 divisors, whose sum is σ = 21354452. Its totient is φ = 21354450.

The previous prime is 21354449. The next prime is 21354551. The reversal of 21354451 is 15445312.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21354451 - 2¹ = 21354449 is a prime.

It is a super-2 number, since 2×21354451² = 912025155022802, which contains 22 as substring.

Together with 21354449, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21354251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10677225 + 10677226.

It is an arithmetic number, because the mean of its divisors is an integer number (10677226).

Almost surely, 2^21354451 is an apocalyptic number.

21354451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21354451 is an equidigital number, since it uses as much as digits as its factorization.

21354451 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2400, while the sum is 25.

The square root of 21354451 is about 4621.0876425361. The cubic root of 21354451 is about 277.4359931374.

Adding to 21354451 its reverse (15445312), we get a palindrome (36799763).

The spelling of 21354451 in words is "twenty-one million, three hundred fifty-four thousand, four hundred fifty-one".