20001321 has 12 divisors (see below), whose sum is σ = 29563248. Its totient is φ = 13023864.

The previous prime is 20001307. The next prime is 20001341. The reversal of 20001321 is 12310002.

It is a happy number.

It is not a de Polignac number, because 20001321 - 2¹⁰ = 20000297 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (20001301) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 25455 + ... + 26228.

It is an arithmetic number, because the mean of its divisors is an integer number (2463604).

Almost surely, 2^20001321 is an apocalyptic number.

It is an amenable number.

20001321 is a deficient number, since it is larger than the sum of its proper divisors (9561927).

20001321 is a wasteful number, since it uses less digits than its factorization.

20001321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51732 (or 51729 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 20001321 is about 4472.2836448508. The cubic root of 20001321 is about 271.4477377707.

Adding to 20001321 its reverse (12310002), we get a palindrome (32311323).

It can be divided in two parts, 2000 and 1321, that added together give a triangular number (3321 = T₈₁).

The spelling of 20001321 in words is "twenty million, one thousand, three hundred twenty-one".