20405401 has 4 divisors (see below), whose sum is σ = 20542500. Its totient is φ = 20268304.

The previous prime is 20405387. The next prime is 20405443. The reversal of 20405401 is 10450402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 10450402 = 2 ⋅5225201.

It can be written as a sum of positive squares in 2 ways, for example, as 13329801 + 7075600 = 3651^2 + 2660^2 .

It is a cyclic number.

It is not a de Polignac number, because 20405401 - 2⁹ = 20404889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20405461) 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, 68326 + ... + 68623.

It is an arithmetic number, because the mean of its divisors is an integer number (5135625).

Almost surely, 2^20405401 is an apocalyptic number.

It is an amenable number.

20405401 is a deficient number, since it is larger than the sum of its proper divisors (137099).

20405401 is a wasteful number, since it uses less digits than its factorization.

20405401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137098.

The product of its (nonzero) digits is 160, while the sum is 16.

The square root of 20405401 is about 4517.2337774350. The cubic root of 20405401 is about 273.2635533089.

Adding to 20405401 its reverse (10450402), we get a palindrome (30855803).

The spelling of 20405401 in words is "twenty million, four hundred five thousand, four hundred one".