21552499 has 2 divisors, whose sum is σ = 21552500. Its totient is φ = 21552498.

The previous prime is 21552497. The next prime is 21552521. The reversal of 21552499 is 99425512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21552499 - 2¹ = 21552497 is a prime.

Together with 21552497, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21552497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10776249 + 10776250.

It is an arithmetic number, because the mean of its divisors is an integer number (10776250).

Almost surely, 2^21552499 is an apocalyptic number.

21552499 is a deficient number, since it is larger than the sum of its proper divisors (1).

21552499 is an equidigital number, since it uses as much as digits as its factorization.

21552499 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32400, while the sum is 37.

The square root of 21552499 is about 4642.4669088751. The cubic root of 21552499 is about 278.2910319337.

The spelling of 21552499 in words is "twenty-one million, five hundred fifty-two thousand, four hundred ninety-nine".