21423497 has 2 divisors, whose sum is σ = 21423498. Its totient is φ = 21423496.

The previous prime is 21423487. The next prime is 21423509. The reversal of 21423497 is 79432412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20620681 + 802816 = 4541^2 + 896^2 .

It is a cyclic number.

It is not a de Polignac number, because 21423497 - 2¹⁰ = 21422473 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21423487) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10711748 + 10711749.

It is an arithmetic number, because the mean of its divisors is an integer number (10711749).

Almost surely, 2^21423497 is an apocalyptic number.

It is an amenable number.

21423497 is a deficient number, since it is larger than the sum of its proper divisors (1).

21423497 is an equidigital number, since it uses as much as digits as its factorization.

21423497 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 32.

The square root of 21423497 is about 4628.5523654810. The cubic root of 21423497 is about 277.7346855405.

The spelling of 21423497 in words is "twenty-one million, four hundred twenty-three thousand, four hundred ninety-seven".