20643259 has 24 divisors (see below), whose sum is σ = 27004320. Its totient is φ = 15611904.

The previous prime is 20643257. The next prime is 20643269. The reversal of 20643259 is 95234602.

It is not a de Polignac number, because 20643259 - 2¹ = 20643257 is a prime.

It is a super-2 number, since 2×20643259² = 852288284282162, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20643259.

It is not an unprimeable number, because it can be changed into a prime (20643251) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13947 + ... + 15355.

It is an arithmetic number, because the mean of its divisors is an integer number (1125180).

Almost surely, 2^20643259 is an apocalyptic number.

20643259 is a deficient number, since it is larger than the sum of its proper divisors (6361061).

20643259 is a wasteful number, since it uses less digits than its factorization.

20643259 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1459 (or 1452 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 31.

The square root of 20643259 is about 4543.4853361709. The cubic root of 20643259 is about 274.3212306879.

It can be divided in two parts, 20643 and 259, that added together give a palindrome (20902).

The spelling of 20643259 in words is "twenty million, six hundred forty-three thousand, two hundred fifty-nine".