20405493 has 8 divisors (see below), whose sum is σ = 30230400. Its totient is φ = 13603644.

The previous prime is 20405479. The next prime is 20405501. The reversal of 20405493 is 39450402.

It is not a de Polignac number, because 20405493 - 2⁵ = 20405461 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 755759 = 20405493 / (2 + 0 + 4 + 0 + 5 + 4 + 9 + 3).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20405443) 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, 377853 + ... + 377906.

It is an arithmetic number, because the mean of its divisors is an integer number (3778800).

Almost surely, 2^20405493 is an apocalyptic number.

It is an amenable number.

20405493 is a deficient number, since it is larger than the sum of its proper divisors (9824907).

20405493 is an equidigital number, since it uses as much as digits as its factorization.

20405493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 755768 (or 755762 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 20405493 is about 4517.2439606468. The cubic root of 20405493 is about 273.2639639879.

Adding to 20405493 its reverse (39450402), we get a palindrome (59855895).

The spelling of 20405493 in words is "twenty million, four hundred five thousand, four hundred ninety-three".