21864757 has 2 divisors, whose sum is σ = 21864758. Its totient is φ = 21864756.

The previous prime is 21864659. The next prime is 21864761. The reversal of 21864757 is 75746812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21169201 + 695556 = 4601^2 + 834^2 .

It is a cyclic number.

It is not a de Polignac number, because 21864757 - 2¹⁵ = 21831989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21864797) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10932378 + 10932379.

It is an arithmetic number, because the mean of its divisors is an integer number (10932379).

Almost surely, 2^21864757 is an apocalyptic number.

It is an amenable number.

21864757 is a deficient number, since it is larger than the sum of its proper divisors (1).

21864757 is an equidigital number, since it uses as much as digits as its factorization.

21864757 is an evil number, because the sum of its binary digits is even.

The product of its digits is 94080, while the sum is 40.

The square root of 21864757 is about 4675.9765824905. The cubic root of 21864757 is about 279.6285763972.

The spelling of 21864757 in words is "twenty-one million, eight hundred sixty-four thousand, seven hundred fifty-seven".