20785121 has 4 divisors (see below), whose sum is σ = 23754432. Its totient is φ = 17815812.

The previous prime is 20785111. The next prime is 20785129. The reversal of 20785121 is 12158702.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12158702 = 2 ⋅6079351.

It is not a de Polignac number, because 20785121 - 2⁶ = 20785057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20785129) 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, 1484645 + ... + 1484658.

It is an arithmetic number, because the mean of its divisors is an integer number (5938608).

Almost surely, 2^20785121 is an apocalyptic number.

It is an amenable number.

20785121 is a deficient number, since it is larger than the sum of its proper divisors (2969311).

20785121 is an equidigital number, since it uses as much as digits as its factorization.

20785121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2969310.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 20785121 is about 4559.0701902910. The cubic root of 20785121 is about 274.9481819721.

The spelling of 20785121 in words is "twenty million, seven hundred eighty-five thousand, one hundred twenty-one".