21238757 has 2 divisors, whose sum is σ = 21238758. Its totient is φ = 21238756.

The previous prime is 21238753. The next prime is 21238843. The reversal of 21238757 is 75783212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20784481 + 454276 = 4559^2 + 674^2 .

It is a cyclic number.

It is not a de Polignac number, because 21238757 - 2² = 21238753 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21238753) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10619378 + 10619379.

It is an arithmetic number, because the mean of its divisors is an integer number (10619379).

Almost surely, 2^21238757 is an apocalyptic number.

It is an amenable number.

21238757 is a deficient number, since it is larger than the sum of its proper divisors (1).

21238757 is an equidigital number, since it uses as much as digits as its factorization.

21238757 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23520, while the sum is 35.

The square root of 21238757 is about 4608.5525927345. The cubic root of 21238757 is about 276.9340552964.

The spelling of 21238757 in words is "twenty-one million, two hundred thirty-eight thousand, seven hundred fifty-seven".