21815553637273 has 12 divisors (see below), whose sum is σ = 24047787628900. Its totient is φ = 19775495314080.

The previous prime is 21815553637253. The next prime is 21815553637331. The reversal of 21815553637273 is 37273635551812.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 18160279974144 + 3655273663129 = 4261488^2 + 1911877^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21815553637273 is a prime.

It is a super-3 number, since 3×21815553637273³ (a number of 41 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21815553637253) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 258258390 + ... + 258342847.

Almost surely, 2^{21815553637273} is an apocalyptic number.

It is an amenable number.

21815553637273 is a deficient number, since it is larger than the sum of its proper divisors (2232233991627).

21815553637273 is a wasteful number, since it uses less digits than its factorization.

21815553637273 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 516601608 (or 516601597 counting only the distinct ones).

The product of its digits is 31752000, while the sum is 58.

The spelling of 21815553637273 in words is "twenty-one trillion, eight hundred fifteen billion, five hundred fifty-three million, six hundred thirty-seven thousand, two hundred seventy-three".