21011800685 has 16 divisors (see below), whose sum is σ = 26334547200. Its totient is φ = 16077917376.

The previous prime is 21011800681. The next prime is 21011800687. The reversal of 21011800685 is 58600811012.

It is a cyclic number.

It is not a de Polignac number, because 21011800685 - 2² = 21011800681 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011800681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 951605 + ... + 973434.

It is an arithmetic number, because the mean of its divisors is an integer number (1645909200).

Almost surely, 2^21011800685 is an apocalyptic number.

It is an amenable number.

21011800685 is a deficient number, since it is larger than the sum of its proper divisors (5322746515).

21011800685 is a wasteful number, since it uses less digits than its factorization.

21011800685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1925140.

The product of its (nonzero) digits is 3840, while the sum is 32.

The spelling of 21011800685 in words is "twenty-one billion, eleven million, eight hundred thousand, six hundred eighty-five".