20726781 has 8 divisors (see below), whose sum is σ = 27853824.
Its totient is φ = 13708800.
The previous prime is 20726779. The next prime is 20726789. The reversal of 20726781 is 18762702.
It is a sphenic number, since it is the product of 3 distinct primes.
It is not a de Polignac number, because 20726781 - 21 = 20726779 is a prime.
It is a super-2 number, since 2×207267812 = 859198901243922, which contains 22 as substring.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (20726789) by changing a digit.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26820 + ... + 27581.
It is an arithmetic number, because the mean of its divisors is an integer number (3481728).
Almost surely, 220726781 is an apocalyptic number.
It is an amenable number.
20726781 is a deficient number, since it is larger than the sum of its proper divisors (7127043).
20726781 is a wasteful number, since it uses less digits than its factorization.
20726781 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 54531.
The product of its (nonzero) digits is 9408, while the sum is 33.
The square root of 20726781 is about 4552.6674598525.
The cubic root of 20726781 is about 274.6906979778.
The spelling of 20726781 in words is "twenty million, seven hundred twenty-six thousand, seven hundred eighty-one".