19621089981 has 6 divisors (see below), whose sum is σ = 28341574430. Its totient is φ = 13080726648.

The previous prime is 19621089979. The next prime is 19621089991. The reversal of 19621089981 is 18998012691.

19621089981 is a `hidden beast` number, since 1 + 9 + 621 + 0 + 8 + 9 + 9 + 8 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 18242824356 + 1378265625 = 135066^2 + 37125^2 .

It is not a de Polignac number, because 19621089981 - 2¹ = 19621089979 is a prime.

It is a super-2 number, since 2×19621089981² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19621089991) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1090060546 + ... + 1090060563.

Almost surely, 2^19621089981 is an apocalyptic number.

It is an amenable number.

19621089981 is a deficient number, since it is larger than the sum of its proper divisors (8720484449).

19621089981 is a wasteful number, since it uses less digits than its factorization.

19621089981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2180121115 (or 2180121112 counting only the distinct ones).

The product of its (nonzero) digits is 559872, while the sum is 54.

The spelling of 19621089981 in words is "nineteen billion, six hundred twenty-one million, eighty-nine thousand, nine hundred eighty-one".