21757951 has 2 divisors, whose sum is σ = 21757952. Its totient is φ = 21757950.

The previous prime is 21757873. The next prime is 21757969. The reversal of 21757951 is 15975712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21757951 - 2¹³ = 21749759 is a prime.

It is a plaindrome in base 8 and base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 21757951.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21757051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10878975 + 10878976.

It is an arithmetic number, because the mean of its divisors is an integer number (10878976).

Almost surely, 2^21757951 is an apocalyptic number.

21757951 is a deficient number, since it is larger than the sum of its proper divisors (1).

21757951 is an equidigital number, since it uses as much as digits as its factorization.

21757951 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22050, while the sum is 37.

The square root of 21757951 is about 4664.5418853302. The cubic root of 21757951 is about 279.1725186962.

The spelling of 21757951 in words is "twenty-one million, seven hundred fifty-seven thousand, nine hundred fifty-one".