21513227 has 2 divisors, whose sum is σ = 21513228. Its totient is φ = 21513226.

The previous prime is 21513209. The next prime is 21513241. The reversal of 21513227 is 72231512.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21513227 is a prime.

It is not a weakly prime, because it can be changed into another prime (21513277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10756613 + 10756614.

It is an arithmetic number, because the mean of its divisors is an integer number (10756614).

Almost surely, 2^21513227 is an apocalyptic number.

21513227 is a deficient number, since it is larger than the sum of its proper divisors (1).

21513227 is an equidigital number, since it uses as much as digits as its factorization.

21513227 is an evil number, because the sum of its binary digits is even.

The product of its digits is 840, while the sum is 23.

The square root of 21513227 is about 4638.2353325376. The cubic root of 21513227 is about 278.1218993384.

Adding to 21513227 its reverse (72231512), we get a palindrome (93744739).

The spelling of 21513227 in words is "twenty-one million, five hundred thirteen thousand, two hundred twenty-seven".