20984861 has 4 divisors (see below), whose sum is σ = 21661824. Its totient is φ = 20307900.

The previous prime is 20984839. The next prime is 20984863. The reversal of 20984861 is 16848902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20984861 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20984863) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 338435 + ... + 338496.

It is an arithmetic number, because the mean of its divisors is an integer number (5415456).

Almost surely, 2^20984861 is an apocalyptic number.

It is an amenable number.

20984861 is a deficient number, since it is larger than the sum of its proper divisors (676963).

20984861 is an equidigital number, since it uses as much as digits as its factorization.

20984861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 676962.

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 20984861 is about 4580.9235968307. The cubic root of 20984861 is about 275.8261043145.

The spelling of 20984861 in words is "twenty million, nine hundred eighty-four thousand, eight hundred sixty-one".