20105921 has 8 divisors (see below), whose sum is σ = 22348224. Its totient is φ = 17932720.

The previous prime is 20105873. The next prime is 20105927. The reversal of 20105921 is 12950102.

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-20105921 is a prime.

It is a super-3 number, since 3×20105921³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20105893 and 20105902.

It is not an unprimeable number, because it can be changed into a prime (20105927) 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, 16661 + ... + 17826.

It is an arithmetic number, because the mean of its divisors is an integer number (2793528).

Almost surely, 2^20105921 is an apocalyptic number.

It is an amenable number.

20105921 is a deficient number, since it is larger than the sum of its proper divisors (2242303).

20105921 is a wasteful number, since it uses less digits than its factorization.

20105921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34551.

The product of its (nonzero) digits is 180, while the sum is 20.

The square root of 20105921 is about 4483.9626448043. The cubic root of 20105921 is about 271.9201079161.

The spelling of 20105921 in words is "twenty million, one hundred five thousand, nine hundred twenty-one".