21322557 has 6 divisors (see below), whose sum is σ = 30799262. Its totient is φ = 14215032.

The previous prime is 21322547. The next prime is 21322571. The reversal of 21322557 is 75522312.

It can be written as a sum of positive squares in only one way, i.e., 20169081 + 1153476 = 4491^2 + 1074^2 .

It is not a de Polignac number, because 21322557 - 2⁶ = 21322493 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21322557.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21322547) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1184578 + ... + 1184595.

Almost surely, 2^21322557 is an apocalyptic number.

It is an amenable number.

21322557 is a deficient number, since it is larger than the sum of its proper divisors (9476705).

21322557 is a wasteful number, since it uses less digits than its factorization.

21322557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2369179 (or 2369176 counting only the distinct ones).

The product of its digits is 4200, while the sum is 27.

The square root of 21322557 is about 4617.6354338557. The cubic root of 21322557 is about 277.2978025485.

Adding to 21322557 its reverse (75522312), we get a palindrome (96844869).

The spelling of 21322557 in words is "twenty-one million, three hundred twenty-two thousand, five hundred fifty-seven".