21387703805 has 8 divisors (see below), whose sum is σ = 27639494232. Its totient is φ = 15793996608.

The previous prime is 21387703801. The next prime is 21387703807. The reversal of 21387703805 is 50830778312.

It can be written as a sum of positive squares in 4 ways, for example, as 38402809 + 21349300996 = 6197^2 + 146114^2 .

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

It is not a de Polignac number, because 21387703805 - 2² = 21387703801 is a prime.

It is a super-2 number, since 2×21387703805² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21387703801) 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, 164520734 + ... + 164520863.

It is an arithmetic number, because the mean of its divisors is an integer number (3454936779).

Almost surely, 2^21387703805 is an apocalyptic number.

It is an amenable number.

21387703805 is a deficient number, since it is larger than the sum of its proper divisors (6251790427).

21387703805 is a wasteful number, since it uses less digits than its factorization.

21387703805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 329041615.

The product of its (nonzero) digits is 282240, while the sum is 44.

The spelling of 21387703805 in words is "twenty-one billion, three hundred eighty-seven million, seven hundred three thousand, eight hundred five".