20666661242 has 4 divisors (see below), whose sum is σ = 30999991866. Its totient is φ = 10333330620.

The previous prime is 20666661229. The next prime is 20666661271. The reversal of 20666661242 is 24216666602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 24216666602 = 2 ⋅12108333301.

It can be written as a sum of positive squares in only one way, i.e., 12802696201 + 7863965041 = 113149^2 + 88679^2 .

It is a super-2 number, since 2×20666661242² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20666661242.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5166665309 + ... + 5166665312.

Almost surely, 2^20666661242 is an apocalyptic number.

20666661242 is a deficient number, since it is larger than the sum of its proper divisors (10333330624).

20666661242 is a wasteful number, since it uses less digits than its factorization.

20666661242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10333330623.

The product of its (nonzero) digits is 248832, while the sum is 41.

The spelling of 20666661242 in words is "twenty billion, six hundred sixty-six million, six hundred sixty-one thousand, two hundred forty-two".