21086757 has 8 divisors (see below), whose sum is σ = 31239680. Its totient is φ = 14057820.

The previous prime is 21086753. The next prime is 21086839. The reversal of 21086757 is 75768012.

It is not a de Polignac number, because 21086757 - 2² = 21086753 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21086753) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 390469 + ... + 390522.

It is an arithmetic number, because the mean of its divisors is an integer number (3904960).

Almost surely, 2^21086757 is an apocalyptic number.

21086757 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21086757 is a deficient number, since it is larger than the sum of its proper divisors (10152923).

21086757 is an equidigital number, since it uses as much as digits as its factorization.

21086757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 781000 (or 780994 counting only the distinct ones).

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

The square root of 21086757 is about 4592.0319031993. The cubic root of 21086757 is about 276.2718257702.

The spelling of 21086757 in words is "twenty-one million, eighty-six thousand, seven hundred fifty-seven".