20261643 has 16 divisors (see below), whose sum is σ = 28849920. Its totient is φ = 12618144.

The previous prime is 20261629. The next prime is 20261687. The reversal of 20261643 is 34616202.

It is not a de Polignac number, because 20261643 - 2¹² = 20257547 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20261743) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 448 + ... + 6381.

It is an arithmetic number, because the mean of its divisors is an integer number (1803120).

Almost surely, 2^20261643 is an apocalyptic number.

20261643 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

20261643 is a deficient number, since it is larger than the sum of its proper divisors (8588277).

20261643 is a wasteful number, since it uses less digits than its factorization.

20261643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6898.

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 20261643 is about 4501.2934807675. The cubic root of 20261643 is about 272.6203177682.

Adding to 20261643 its reverse (34616202), we get a palindrome (54877845).

The spelling of 20261643 in words is "twenty million, two hundred sixty-one thousand, six hundred forty-three".