21511811285 has 8 divisors (see below), whose sum is σ = 26511854136. Its totient is φ = 16744328640.

The previous prime is 21511811273. The next prime is 21511811323. The reversal of 21511811285 is 58211811512.

It can be written as a sum of positive squares in 4 ways, for example, as 3795668881 + 17716142404 = 61609^2 + 133102^2 .

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

It is not a de Polignac number, because 21511811285 - 2¹⁰ = 21511810261 is a prime.

It is a super-2 number, since 2×21511811285² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 58139846 + ... + 58140215.

It is an arithmetic number, because the mean of its divisors is an integer number (3313981767).

Almost surely, 2^21511811285 is an apocalyptic number.

It is an amenable number.

21511811285 is a deficient number, since it is larger than the sum of its proper divisors (5000042851).

21511811285 is a wasteful number, since it uses less digits than its factorization.

21511811285 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116280103.

The product of its digits is 6400, while the sum is 35.

The spelling of 21511811285 in words is "twenty-one billion, five hundred eleven million, eight hundred eleven thousand, two hundred eighty-five".