20643001 has 4 divisors (see below), whose sum is σ = 20702500. Its totient is φ = 20583504.

The previous prime is 20642971. The next prime is 20643043. The reversal of 20643001 is 10034602.

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 18696976 + 1946025 = 4324^2 + 1395^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20643001 is a prime.

It is a super-2 number, since 2×20643001² = 852266980572002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20643061) 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, 29226 + ... + 29923.

It is an arithmetic number, because the mean of its divisors is an integer number (5175625).

Almost surely, 2^20643001 is an apocalyptic number.

It is an amenable number.

20643001 is a deficient number, since it is larger than the sum of its proper divisors (59499).

20643001 is an equidigital number, since it uses as much as digits as its factorization.

20643001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59498.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 20643001 is about 4543.4569437819. The cubic root of 20643001 is about 274.3200878584.

Adding to 20643001 its reverse (10034602), we get a palindrome (30677603).

The spelling of 20643001 in words is "twenty million, six hundred forty-three thousand, one".