20784981 has 8 divisors (see below), whose sum is σ = 31672384. Its totient is φ = 11877120.

The previous prime is 20784923. The next prime is 20785007. The reversal of 20784981 is 18948702.

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

It is not a de Polignac number, because 20784981 - 2¹⁰ = 20783957 is a prime.

It is a super-2 number, since 2×20784981² = 864030870340722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20784901) 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, 494860 + ... + 494901.

It is an arithmetic number, because the mean of its divisors is an integer number (3959048).

Almost surely, 2^20784981 is an apocalyptic number.

20784981 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20784981 is a deficient number, since it is larger than the sum of its proper divisors (10887403).

20784981 is an equidigital number, since it uses as much as digits as its factorization.

20784981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 989771.

The product of its (nonzero) digits is 32256, while the sum is 39.

The square root of 20784981 is about 4559.0548362572. The cubic root of 20784981 is about 274.9475646582.

The spelling of 20784981 in words is "twenty million, seven hundred eighty-four thousand, nine hundred eighty-one".