21682757 has 2 divisors, whose sum is σ = 21682758. Its totient is φ = 21682756.

The previous prime is 21682709. The next prime is 21682823. The reversal of 21682757 is 75728612.

21682757 is nontrivially palindromic in base 5.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16638241 + 5044516 = 4079^2 + 2246^2 .

It is a cyclic number.

It is not a de Polignac number, because 21682757 - 2⁶ = 21682693 is a prime.

It is a super-2 number, since 2×21682757² = 940283902242098, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21682757.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21682057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10841378 + 10841379.

It is an arithmetic number, because the mean of its divisors is an integer number (10841379).

Almost surely, 2^21682757 is an apocalyptic number.

It is an amenable number.

21682757 is a deficient number, since it is larger than the sum of its proper divisors (1).

21682757 is an equidigital number, since it uses as much as digits as its factorization.

21682757 is an evil number, because the sum of its binary digits is even.

The product of its digits is 47040, while the sum is 38.

The square root of 21682757 is about 4656.4747395428. The cubic root of 21682757 is about 278.8505470894.

The spelling of 21682757 in words is "twenty-one million, six hundred eighty-two thousand, seven hundred fifty-seven".