20800557 has 16 divisors (see below), whose sum is σ = 31199360. Its totient is φ = 13865580.

The previous prime is 20800553. The next prime is 20800561. The reversal of 20800557 is 75500802.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20800553) and next prime (20800561).

It is not a de Polignac number, because 20800557 - 2² = 20800553 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

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 20800557.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20800553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2569 + ... + 6942.

It is an arithmetic number, because the mean of its divisors is an integer number (1949960).

Almost surely, 2^20800557 is an apocalyptic number.

20800557 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

20800557 is a deficient number, since it is larger than the sum of its proper divisors (10398803).

20800557 is an frugal number, since it uses more digits than its factorization.

20800557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9532 (or 9514 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 27.

The square root of 20800557 is about 4560.7627651523. The cubic root of 20800557 is about 275.0162282434.

The spelling of 20800557 in words is "twenty million, eight hundred thousand, five hundred fifty-seven".