20421555555 has 8 divisors (see below), whose sum is σ = 32674488912. Its totient is φ = 10891496288.

The previous prime is 20421555533. The next prime is 20421555593. The reversal of 20421555555 is 55555512402.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20421555555 - 2¹⁵ = 20421522787 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 680718504 + ... + 680718533.

It is an arithmetic number, because the mean of its divisors is an integer number (4084311114).

Almost surely, 2^20421555555 is an apocalyptic number.

20421555555 is a deficient number, since it is larger than the sum of its proper divisors (12252933357).

20421555555 is a wasteful number, since it uses less digits than its factorization.

20421555555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1361437045.

The product of its (nonzero) digits is 250000, while the sum is 39.

The spelling of 20421555555 in words is "twenty billion, four hundred twenty-one million, five hundred fifty-five thousand, five hundred fifty-five".