20355861 has 4 divisors (see below), whose sum is σ = 27141152. Its totient is φ = 13570572.

The previous prime is 20355847. The next prime is 20355877. The reversal of 20355861 is 16855302.

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 not a de Polignac number, because 20355861 - 2⁷ = 20355733 is a prime.

It is a super-2 number, since 2×20355861² = 828722154102642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20355961) 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 3 ways as a sum of consecutive naturals, for example, 3392641 + ... + 3392646.

It is an arithmetic number, because the mean of its divisors is an integer number (6785288).

Almost surely, 2^20355861 is an apocalyptic number.

It is an amenable number.

20355861 is a deficient number, since it is larger than the sum of its proper divisors (6785291).

20355861 is an equidigital number, since it uses as much as digits as its factorization.

20355861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6785290.

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 20355861 is about 4511.7470008856. The cubic root of 20355861 is about 273.0422320582.

The spelling of 20355861 in words is "twenty million, three hundred fifty-five thousand, eight hundred sixty-one".