20181261 has 16 divisors (see below), whose sum is σ = 28857600. Its totient is φ = 12499968.

The previous prime is 20181247. The next prime is 20181311. The reversal of 20181261 is 16218102.

It is not a de Polignac number, because 20181261 - 2⁵ = 20181229 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20185261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1525 + ... + 6533.

It is an arithmetic number, because the mean of its divisors is an integer number (1803600).

Almost surely, 2^20181261 is an apocalyptic number.

It is an amenable number.

20181261 is a deficient number, since it is larger than the sum of its proper divisors (8676339).

20181261 is a wasteful number, since it uses less digits than its factorization.

20181261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5108.

The product of its (nonzero) digits is 192, while the sum is 21.

The square root of 20181261 is about 4492.3558407588. The cubic root of 20181261 is about 272.2593268195.

Adding to 20181261 its reverse (16218102), we get a palindrome (36399363).

The spelling of 20181261 in words is "twenty million, one hundred eighty-one thousand, two hundred sixty-one".