21422451 has 4 divisors (see below), whose sum is σ = 28563272. Its totient is φ = 14281632.

The previous prime is 21422449. The next prime is 21422461. The reversal of 21422451 is 15422412.

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

It is not a de Polignac number, because 21422451 - 2¹ = 21422449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21422411) 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, 3570406 + ... + 3570411.

It is an arithmetic number, because the mean of its divisors is an integer number (7140818).

Almost surely, 2^21422451 is an apocalyptic number.

21422451 is a deficient number, since it is larger than the sum of its proper divisors (7140821).

21422451 is an equidigital number, since it uses as much as digits as its factorization.

21422451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7140820.

The product of its digits is 640, while the sum is 21.

The square root of 21422451 is about 4628.4393698092. The cubic root of 21422451 is about 277.7301653447.

Adding to 21422451 its reverse (15422412), we get a palindrome (36844863).

The spelling of 21422451 in words is "twenty-one million, four hundred twenty-two thousand, four hundred fifty-one".