20404621 has 4 divisors (see below), whose sum is σ = 20413692. Its totient is φ = 20395552.

The previous prime is 20404591. The next prime is 20404679. The reversal of 20404621 is 12640402.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 12075625 + 8328996 = 3475^2 + 2886^2 .

It is a cyclic number.

It is not a de Polignac number, because 20404621 - 2⁵ = 20404589 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 (20404421) 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, 1665 + ... + 6601.

It is an arithmetic number, because the mean of its divisors is an integer number (5103423).

Almost surely, 2^20404621 is an apocalyptic number.

It is an amenable number.

20404621 is a deficient number, since it is larger than the sum of its proper divisors (9071).

20404621 is an equidigital number, since it uses as much as digits as its factorization.

20404621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9070.

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 20404621 is about 4517.1474405868. The cubic root of 20404621 is about 273.2600714156.

It can be divided in two parts, 20404 and 621, that added together give a square (21025 = 145²).

The spelling of 20404621 in words is "twenty million, four hundred four thousand, six hundred twenty-one".