21928757 has 2 divisors, whose sum is σ = 21928758. Its totient is φ = 21928756.

The previous prime is 21928733. The next prime is 21928763. The reversal of 21928757 is 75782912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19018321 + 2910436 = 4361^2 + 1706^2 .

It is a cyclic number.

It is not a de Polignac number, because 21928757 - 2¹⁰ = 21927733 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21928787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10964378 + 10964379.

It is an arithmetic number, because the mean of its divisors is an integer number (10964379).

Almost surely, 2^21928757 is an apocalyptic number.

It is an amenable number.

21928757 is a deficient number, since it is larger than the sum of its proper divisors (1).

21928757 is an equidigital number, since it uses as much as digits as its factorization.

21928757 is an evil number, because the sum of its binary digits is even.

The product of its digits is 70560, while the sum is 41.

The square root of 21928757 is about 4682.8150721548. The cubic root of 21928757 is about 279.9011428225.

The spelling of 21928757 in words is "twenty-one million, nine hundred twenty-eight thousand, seven hundred fifty-seven".