20641421 has 4 divisors (see below), whose sum is σ = 20755644. Its totient is φ = 20527200.

The previous prime is 20641403. The next prime is 20641457. The reversal of 20641421 is 12414602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12414602 = 2 ⋅6207301.

It can be written as a sum of positive squares in 2 ways, for example, as 972196 + 19669225 = 986^2 + 4435^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20641421 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20641393 and 20641402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20641721) 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, 56840 + ... + 57201.

It is an arithmetic number, because the mean of its divisors is an integer number (5188911).

Almost surely, 2^20641421 is an apocalyptic number.

It is an amenable number.

20641421 is a deficient number, since it is larger than the sum of its proper divisors (114223).

20641421 is a wasteful number, since it uses less digits than its factorization.

20641421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114222.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 20641421 is about 4543.2830640408. The cubic root of 20641421 is about 274.3130889278.

The spelling of 20641421 in words is "twenty million, six hundred forty-one thousand, four hundred twenty-one".