21369247 has 2 divisors, whose sum is σ = 21369248. Its totient is φ = 21369246.

The previous prime is 21369223. The next prime is 21369253. The reversal of 21369247 is 74296312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21369247 - 2¹⁹ = 20844959 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21369847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10684623 + 10684624.

It is an arithmetic number, because the mean of its divisors is an integer number (10684624).

Almost surely, 2^21369247 is an apocalyptic number.

21369247 is a deficient number, since it is larger than the sum of its proper divisors (1).

21369247 is an equidigital number, since it uses as much as digits as its factorization.

21369247 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 34.

The square root of 21369247 is about 4622.6882871334. The cubic root of 21369247 is about 277.5000546492.

The spelling of 21369247 in words is "twenty-one million, three hundred sixty-nine thousand, two hundred forty-seven".