21422251 has 8 divisors (see below), whose sum is σ = 21879360. Its totient is φ = 20968392.

The previous prime is 21422231. The next prime is 21422273. The reversal of 21422251 is 15222412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21422251 - 2¹⁵ = 21389483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21422221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16056 + ... + 17338.

It is an arithmetic number, because the mean of its divisors is an integer number (2734920).

Almost surely, 2^21422251 is an apocalyptic number.

21422251 is a deficient number, since it is larger than the sum of its proper divisors (457109).

21422251 is a wasteful number, since it uses less digits than its factorization.

21422251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1625.

The product of its digits is 320, while the sum is 19.

The square root of 21422251 is about 4628.4177642041. The cubic root of 21422251 is about 277.7293010457.

Adding to 21422251 its reverse (15222412), we get a palindrome (36644663).

The spelling of 21422251 in words is "twenty-one million, four hundred twenty-two thousand, two hundred fifty-one".