20666661243 has 16 divisors (see below), whose sum is σ = 27693431040. Its totient is φ = 13708959264.

The previous prime is 20666661229. The next prime is 20666661271. The reversal of 20666661243 is 34216666602.

It is not a de Polignac number, because 20666661243 - 2⁶ = 20666661179 is a prime.

It is a super-2 number, since 2×20666661243² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20666661195 and 20666661204.

It is not an unprimeable number, because it can be changed into a prime (20666661343) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 662505 + ... + 692997.

It is an arithmetic number, because the mean of its divisors is an integer number (1730839440).

Almost surely, 2^20666661243 is an apocalyptic number.

20666661243 is a deficient number, since it is larger than the sum of its proper divisors (7026769797).

20666661243 is a wasteful number, since it uses less digits than its factorization.

20666661243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31618.

The product of its (nonzero) digits is 373248, while the sum is 42.

The spelling of 20666661243 in words is "twenty billion, six hundred sixty-six million, six hundred sixty-one thousand, two hundred forty-three".