21680757 has 16 divisors (see below), whose sum is σ = 36708480. Its totient is φ = 12388896.

The previous prime is 21680741. The next prime is 21680783. The reversal of 21680757 is 75708612.

It is not a de Polignac number, because 21680757 - 2⁴ = 21680741 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21680707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 57168 + ... + 57545.

It is an arithmetic number, because the mean of its divisors is an integer number (2294280).

Almost surely, 2^21680757 is an apocalyptic number.

21680757 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21680757 is a deficient number, since it is larger than the sum of its proper divisors (15027723).

21680757 is a wasteful number, since it uses less digits than its factorization.

21680757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114729 (or 114723 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The square root of 21680757 is about 4656.2599798551. The cubic root of 21680757 is about 278.8419731760.

The spelling of 21680757 in words is "twenty-one million, six hundred eighty thousand, seven hundred fifty-seven".