21601757 has 2 divisors, whose sum is σ = 21601758. Its totient is φ = 21601756.

The previous prime is 21601721. The next prime is 21601759. The reversal of 21601757 is 75710612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20016676 + 1585081 = 4474^2 + 1259^2 .

It is a cyclic number.

It is not a de Polignac number, because 21601757 - 2⁶ = 21601693 is a prime.

Together with 21601759, it forms a pair of twin primes.

It is a Chen prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21601759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10800878 + 10800879.

It is an arithmetic number, because the mean of its divisors is an integer number (10800879).

Almost surely, 2^21601757 is an apocalyptic number.

It is an amenable number.

21601757 is a deficient number, since it is larger than the sum of its proper divisors (1).

21601757 is an equidigital number, since it uses as much as digits as its factorization.

21601757 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2940, while the sum is 29.

The square root of 21601757 is about 4647.7690347090. The cubic root of 21601757 is about 278.5028809894.

The spelling of 21601757 in words is "twenty-one million, six hundred one thousand, seven hundred fifty-seven".