20781611 has 8 divisors (see below), whose sum is σ = 21955920. Its totient is φ = 19615392.

The previous prime is 20781583. The next prime is 20781617. The reversal of 20781611 is 11618702.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20781611 is a prime.

It is a Duffinian number.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (20781617) 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 7 ways as a sum of consecutive naturals, for example, 3701 + ... + 7433.

It is an arithmetic number, because the mean of its divisors is an integer number (2744490).

Almost surely, 2^20781611 is an apocalyptic number.

20781611 is a deficient number, since it is larger than the sum of its proper divisors (1174309).

20781611 is a wasteful number, since it uses less digits than its factorization.

20781611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4045.

The product of its (nonzero) digits is 672, while the sum is 26.

The square root of 20781611 is about 4558.6852271242. The cubic root of 20781611 is about 274.9327041944.

It can be divided in two parts, 207 and 81611, that added together give a palindrome (81818).

The spelling of 20781611 in words is "twenty million, seven hundred eighty-one thousand, six hundred eleven".