21322551 has 8 divisors (see below), whose sum is σ = 28536064. Its totient is φ = 14162040.

The previous prime is 21322547. The next prime is 21322571. The reversal of 21322551 is 15522312.

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

It is not a de Polignac number, because 21322551 - 2² = 21322547 is a prime.

It is a super-2 number, since 2×21322551² = 909302362295202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21322571) 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, 12301 + ... + 13926.

It is an arithmetic number, because the mean of its divisors is an integer number (3567008).

Almost surely, 2^21322551 is an apocalyptic number.

21322551 is a deficient number, since it is larger than the sum of its proper divisors (7213513).

21322551 is a wasteful number, since it uses less digits than its factorization.

21322551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26501.

The product of its digits is 600, while the sum is 21.

The square root of 21322551 is about 4617.6347841725. The cubic root of 21322551 is about 277.2977765387.

Adding to 21322551 its reverse (15522312), we get a palindrome (36844863).

The spelling of 21322551 in words is "twenty-one million, three hundred twenty-two thousand, five hundred fifty-one".