20155840 has 28 divisors (see below), whose sum is σ = 47996856. Its totient is φ = 8062208.

The previous prime is 20155831. The next prime is 20155867. The reversal of 20155840 is 4855102.

It is a super-2 number, since 2×20155840² = 812515772211200, which contains 22 as substring.

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, 31174 + ... + 31813.

Almost surely, 2^20155840 is an apocalyptic number.

20155840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20155840 is an abundant number, since it is smaller than the sum of its proper divisors (27841016).

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

20155840 is an equidigital number, since it uses as much as digits as its factorization.

20155840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63004 (or 62994 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 25.

The square root of 20155840 is about 4489.5255874090. The cubic root of 20155840 is about 272.1449630969.

The spelling of 20155840 in words is "twenty million, one hundred fifty-five thousand, eight hundred forty".