20841557 has 4 divisors (see below), whose sum is σ = 22736256. Its totient is φ = 18946860.

The previous prime is 20841547. The next prime is 20841577. The reversal of 20841557 is 75514802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20841557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20841547) by changing a digit.

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, 947333 + ... + 947354.

It is an arithmetic number, because the mean of its divisors is an integer number (5684064).

Almost surely, 2^20841557 is an apocalyptic number.

It is an amenable number.

20841557 is a deficient number, since it is larger than the sum of its proper divisors (1894699).

20841557 is a wasteful number, since it uses less digits than its factorization.

20841557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1894698.

The product of its (nonzero) digits is 11200, while the sum is 32.

The square root of 20841557 is about 4565.2554145414. The cubic root of 20841557 is about 275.1968045772.

The spelling of 20841557 in words is "twenty million, eight hundred forty-one thousand, five hundred fifty-seven".