21742793 has 2 divisors, whose sum is σ = 21742794. Its totient is φ = 21742792.

The previous prime is 21742771. The next prime is 21742817. The reversal of 21742793 is 39724712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16711744 + 5031049 = 4088^2 + 2243^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21742793 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21742753) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10871396 + 10871397.

It is an arithmetic number, because the mean of its divisors is an integer number (10871397).

Almost surely, 2^21742793 is an apocalyptic number.

It is an amenable number.

21742793 is a deficient number, since it is larger than the sum of its proper divisors (1).

21742793 is an equidigital number, since it uses as much as digits as its factorization.

21742793 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21168, while the sum is 35.

The square root of 21742793 is about 4662.9167910225. The cubic root of 21742793 is about 279.1076737404.

The spelling of 21742793 in words is "twenty-one million, seven hundred forty-two thousand, seven hundred ninety-three".