20521903 has 4 divisors (see below), whose sum is σ = 20548080. Its totient is φ = 20495728.

The previous prime is 20521889. The next prime is 20521967. The reversal of 20521903 is 30912502.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20521903 - 2⁵ = 20521871 is a prime.

It is a super-2 number, since 2×20521903² = 842297005482818, 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 (20521603) 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, 11875 + ... + 13492.

It is an arithmetic number, because the mean of its divisors is an integer number (5137020).

Almost surely, 2^20521903 is an apocalyptic number.

20521903 is a deficient number, since it is larger than the sum of its proper divisors (26177).

20521903 is an equidigital number, since it uses as much as digits as its factorization.

20521903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26176.

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 20521903 is about 4530.1107050490. The cubic root of 20521903 is about 273.7826210231.

The spelling of 20521903 in words is "twenty million, five hundred twenty-one thousand, nine hundred three".