21324739 has 2 divisors, whose sum is σ = 21324740. Its totient is φ = 21324738.

The previous prime is 21324733. The next prime is 21324761. The reversal of 21324739 is 93742312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21324739 - 2⁹ = 21324227 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21324739.

It is not a weakly prime, because it can be changed into another prime (21324733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10662369 + 10662370.

It is an arithmetic number, because the mean of its divisors is an integer number (10662370).

Almost surely, 2^21324739 is an apocalyptic number.

21324739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21324739 is an equidigital number, since it uses as much as digits as its factorization.

21324739 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9072, while the sum is 31.

The square root of 21324739 is about 4617.8716959223. The cubic root of 21324739 is about 277.3072611259.

The spelling of 21324739 in words is "twenty-one million, three hundred twenty-four thousand, seven hundred thirty-nine".