20402555 has 4 divisors (see below), whose sum is σ = 24483072. Its totient is φ = 16322040.

The previous prime is 20402537. The next prime is 20402563. The reversal of 20402555 is 55520402.

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

It is not a de Polignac number, because 20402555 - 2⁶ = 20402491 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20402555.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2040251 + ... + 2040260.

It is an arithmetic number, because the mean of its divisors is an integer number (6120768).

Almost surely, 2^20402555 is an apocalyptic number.

20402555 is a deficient number, since it is larger than the sum of its proper divisors (4080517).

20402555 is an equidigital number, since it uses as much as digits as its factorization.

20402555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4080516.

The product of its (nonzero) digits is 2000, while the sum is 23.

The square root of 20402555 is about 4516.9187506529. The cubic root of 20402555 is about 273.2508484335.

Adding to 20402555 its reverse (55520402), we get a palindrome (75922957).

The spelling of 20402555 in words is "twenty million, four hundred two thousand, five hundred fifty-five".