21019845685 has 8 divisors (see below), whose sum is σ = 26093601720. Its totient is φ = 16236018624.

The previous prime is 21019845661. The next prime is 21019845727. The reversal of 21019845685 is 58654891012.

It can be written as a sum of positive squares in 4 ways, for example, as 3901001764 + 17118843921 = 62458^2 + 130839^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21019845685 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 72482082 + ... + 72482371.

It is an arithmetic number, because the mean of its divisors is an integer number (3261700215).

Almost surely, 2^21019845685 is an apocalyptic number.

It is an amenable number.

21019845685 is a deficient number, since it is larger than the sum of its proper divisors (5073756035).

21019845685 is a wasteful number, since it uses less digits than its factorization.

21019845685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144964487.

The product of its (nonzero) digits is 691200, while the sum is 49.

The spelling of 21019845685 in words is "twenty-one billion, nineteen million, eight hundred forty-five thousand, six hundred eighty-five".