20511013555 has 4 divisors (see below), whose sum is σ = 24613216272. Its totient is φ = 16408810840.

The previous prime is 20511013547. The next prime is 20511013559. The reversal of 20511013555 is 55531011502.

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

It is not a de Polignac number, because 20511013555 - 2³ = 20511013547 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20511013559) 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, 2051101351 + ... + 2051101360.

It is an arithmetic number, because the mean of its divisors is an integer number (6153304068).

Almost surely, 2^20511013555 is an apocalyptic number.

20511013555 is a deficient number, since it is larger than the sum of its proper divisors (4102202717).

20511013555 is an equidigital number, since it uses as much as digits as its factorization.

20511013555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4102202716.

The product of its (nonzero) digits is 3750, while the sum is 28.

The spelling of 20511013555 in words is "twenty billion, five hundred eleven million, thirteen thousand, five hundred fifty-five".