21552913 has 2 divisors, whose sum is σ = 21552914. Its totient is φ = 21552912.

The previous prime is 21552911. The next prime is 21552919. The reversal of 21552913 is 31925512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15116544 + 6436369 = 3888^2 + 2537^2 .

It is a cyclic number.

It is not a de Polignac number, because 21552913 - 2¹ = 21552911 is a prime.

Together with 21552911, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21552911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10776456 + 10776457.

It is an arithmetic number, because the mean of its divisors is an integer number (10776457).

Almost surely, 2^21552913 is an apocalyptic number.

It is an amenable number.

21552913 is a deficient number, since it is larger than the sum of its proper divisors (1).

21552913 is an equidigital number, since it uses as much as digits as its factorization.

21552913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2700, while the sum is 28.

The square root of 21552913 is about 4642.5114970240. The cubic root of 21552913 is about 278.2928138114.

The spelling of 21552913 in words is "twenty-one million, five hundred fifty-two thousand, nine hundred thirteen".