20001397 has 4 divisors (see below), whose sum is σ = 21539980. Its totient is φ = 18462816.

The previous prime is 20001389. The next prime is 20001439. The reversal of 20001397 is 79310002.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8071281 + 11930116 = 2841^2 + 3454^2 .

It is a cyclic number.

It is not a de Polignac number, because 20001397 - 2³ = 20001389 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 (20001307) 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, 769272 + ... + 769297.

It is an arithmetic number, because the mean of its divisors is an integer number (5384995).

Almost surely, 2^20001397 is an apocalyptic number.

It is an amenable number.

20001397 is a deficient number, since it is larger than the sum of its proper divisors (1538583).

20001397 is a wasteful number, since it uses less digits than its factorization.

20001397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1538582.

The product of its (nonzero) digits is 378, while the sum is 22.

The square root of 20001397 is about 4472.2921416204. The cubic root of 20001397 is about 271.4480815814.

Adding to 20001397 its reverse (79310002), we get a palindrome (99311399).

The spelling of 20001397 in words is "twenty million, one thousand, three hundred ninety-seven".