20513555 has 4 divisors (see below), whose sum is σ = 24616272. Its totient is φ = 16410840.

The previous prime is 20513551. The next prime is 20513557. The reversal of 20513555 is 55531502.

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

It is not a de Polignac number, because 20513555 - 2² = 20513551 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20513551) 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, 2051351 + ... + 2051360.

It is an arithmetic number, because the mean of its divisors is an integer number (6154068).

Almost surely, 2^20513555 is an apocalyptic number.

20513555 is a deficient number, since it is larger than the sum of its proper divisors (4102717).

20513555 is an equidigital number, since it uses as much as digits as its factorization.

20513555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4102716.

The product of its (nonzero) digits is 3750, while the sum is 26.

The square root of 20513555 is about 4529.1892210417. The cubic root of 20513555 is about 273.7454924440.

The spelling of 20513555 in words is "twenty million, five hundred thirteen thousand, five hundred fifty-five".