21757079 has 2 divisors, whose sum is σ = 21757080. Its totient is φ = 21757078.

The previous prime is 21757051. The next prime is 21757091. The reversal of 21757079 is 97075712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21757079 - 2¹⁶ = 21691543 is a prime.

It is a super-2 number, since 2×21757079² = 946740973224482, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21757049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10878539 + 10878540.

It is an arithmetic number, because the mean of its divisors is an integer number (10878540).

Almost surely, 2^21757079 is an apocalyptic number.

21757079 is a deficient number, since it is larger than the sum of its proper divisors (1).

21757079 is an equidigital number, since it uses as much as digits as its factorization.

21757079 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30870, while the sum is 38.

The square root of 21757079 is about 4664.4484132639. The cubic root of 21757079 is about 279.1687891524.

The spelling of 21757079 in words is "twenty-one million, seven hundred fifty-seven thousand, seventy-nine".