20591861 has 4 divisors (see below), whose sum is σ = 20604000. Its totient is φ = 20579724.

The previous prime is 20591833. The next prime is 20591873. The reversal of 20591861 is 16819502.

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-20591861 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 (20591891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3011 + ... + 7088.

It is an arithmetic number, because the mean of its divisors is an integer number (5151000).

Almost surely, 2^20591861 is an apocalyptic number.

It is an amenable number.

20591861 is a deficient number, since it is larger than the sum of its proper divisors (12139).

20591861 is a wasteful number, since it uses less digits than its factorization.

20591861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12138.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 20591861 is about 4537.8255806058. The cubic root of 20591861 is about 274.0933713074.

The spelling of 20591861 in words is "twenty million, five hundred ninety-one thousand, eight hundred sixty-one".