20718861 has 8 divisors (see below), whose sum is σ = 27808704. Its totient is φ = 13720800.

The previous prime is 20718857. The next prime is 20718871. The reversal of 20718861 is 16881702.

It is a happy number.

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

It is not a de Polignac number, because 20718861 - 2² = 20718857 is a prime.

It is a super-2 number, since 2×20718861² = 858542402274642, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20718851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22416 + ... + 23321.

It is an arithmetic number, because the mean of its divisors is an integer number (3476088).

Almost surely, 2^20718861 is an apocalyptic number.

It is an amenable number.

20718861 is a deficient number, since it is larger than the sum of its proper divisors (7089843).

20718861 is a wasteful number, since it uses less digits than its factorization.

20718861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45891.

The product of its (nonzero) digits is 5376, while the sum is 33.

The square root of 20718861 is about 4551.7975570098. The cubic root of 20718861 is about 274.6557057699.

The spelling of 20718861 in words is "twenty million, seven hundred eighteen thousand, eight hundred sixty-one".