20021668551 has 48 divisors (see below), whose sum is σ = 30644490240. Its totient is φ = 12561626880.

The previous prime is 20021668547. The next prime is 20021668561. The reversal of 20021668551 is 15586612002.

20021668551 is a `hidden beast` number, since 20 + 0 + 21 + 6 + 68 + 551 = 666.

It is not a de Polignac number, because 20021668551 - 2² = 20021668547 is a prime.

It is a super-2 number, since 2×20021668551² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021668561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 22725631 + ... + 22726511.

It is an arithmetic number, because the mean of its divisors is an integer number (638426880).

Almost surely, 2^20021668551 is an apocalyptic number.

20021668551 is a deficient number, since it is larger than the sum of its proper divisors (10622821689).

20021668551 is a wasteful number, since it uses less digits than its factorization.

20021668551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1636 (or 1633 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The spelling of 20021668551 in words is "twenty billion, twenty-one million, six hundred sixty-eight thousand, five hundred fifty-one".