21181640468 has 12 divisors (see below), whose sum is σ = 37158504180. Its totient is φ = 10564924992.

The previous prime is 21181640461. The next prime is 21181640471. The reversal of 21181640468 is 86404618112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 18831523984 + 2350116484 = 137228^2 + 48478^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21181640461) 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 3 ways as a sum of consecutive naturals, for example, 6471971 + ... + 6475242.

It is an arithmetic number, because the mean of its divisors is an integer number (3096542015).

Almost surely, 2^21181640468 is an apocalyptic number.

It is an amenable number.

21181640468 is a deficient number, since it is larger than the sum of its proper divisors (15976863712).

21181640468 is a wasteful number, since it uses less digits than its factorization.

21181640468 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12947626 (or 12947624 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 41.

The spelling of 21181640468 in words is "twenty-one billion, one hundred eighty-one million, six hundred forty thousand, four hundred sixty-eight".