20556555499 has 4 divisors (see below), whose sum is σ = 21765764664. Its totient is φ = 19347346336.

The previous prime is 20556555433. The next prime is 20556555511. The reversal of 20556555499 is 99455565502.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20556555499 - 2¹³ = 20556547307 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20556555599) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 604604557 + ... + 604604590.

It is an arithmetic number, because the mean of its divisors is an integer number (5441441166).

Almost surely, 2^20556555499 is an apocalyptic number.

20556555499 is a deficient number, since it is larger than the sum of its proper divisors (1209209165).

20556555499 is a wasteful number, since it uses less digits than its factorization.

20556555499 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1209209164.

The product of its (nonzero) digits is 12150000, while the sum is 55.

The spelling of 20556555499 in words is "twenty billion, five hundred fifty-six million, five hundred fifty-five thousand, four hundred ninety-nine".