20451921 has 8 divisors (see below), whose sum is σ = 31164864. Its totient is φ = 11686800.

The previous prime is 20451917. The next prime is 20451929. The reversal of 20451921 is 12915402.

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

It is not a de Polignac number, because 20451921 - 2² = 20451917 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20451891 and 20451900.

It is not an unprimeable number, because it can be changed into a prime (20451929) 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, 486930 + ... + 486971.

It is an arithmetic number, because the mean of its divisors is an integer number (3895608).

Almost surely, 2^20451921 is an apocalyptic number.

20451921 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20451921 is a deficient number, since it is larger than the sum of its proper divisors (10712943).

20451921 is an equidigital number, since it uses as much as digits as its factorization.

20451921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 973911.

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 20451921 is about 4522.3800149921. The cubic root of 20451921 is about 273.4710567426.

It can be divided in two parts, 204 and 51921, that added together give a palindrome (52125).

The spelling of 20451921 in words is "twenty million, four hundred fifty-one thousand, nine hundred twenty-one".