20172856 has 16 divisors (see below), whose sum is σ = 41262840. Its totient is φ = 9169440.

The previous prime is 20172827. The next prime is 20172877. The reversal of 20172856 is 65827102.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 114531 + ... + 114706.

Almost surely, 2^20172856 is an apocalyptic number.

It is an amenable number.

20172856 is an abundant number, since it is smaller than the sum of its proper divisors (21089984).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20172856 is a wasteful number, since it uses less digits than its factorization.

20172856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 229254 (or 229250 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 20172856 is about 4491.4202653504. The cubic root of 20172856 is about 272.2215251282.

Adding to 20172856 its reverse (65827102), we get a palindrome (85999958).

The spelling of 20172856 in words is "twenty million, one hundred seventy-two thousand, eight hundred fifty-six".