20149818561 has 12 divisors (see below), whose sum is σ = 29106572560. Its totient is φ = 13432622040.

The previous prime is 20149818551. The next prime is 20149818583. The reversal of 20149818561 is 16581894102.

It is a happy number.

20149818561 is a `hidden beast` number, since 2 + 0 + 1 + 4 + 9 + 81 + 8 + 561 = 666.

It is not a de Polignac number, because 20149818561 - 2⁵ = 20149818529 is a prime.

It is a super-2 number, since 2×20149818561² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20149818511) 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, 290250 + ... + 352908.

Almost surely, 2^20149818561 is an apocalyptic number.

It is an amenable number.

20149818561 is a deficient number, since it is larger than the sum of its proper divisors (8956753999).

20149818561 is a wasteful number, since it uses less digits than its factorization.

20149818561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98396 (or 98393 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 45.

The spelling of 20149818561 in words is "twenty billion, one hundred forty-nine million, eight hundred eighteen thousand, five hundred sixty-one".