20400505 has 8 divisors (see below), whose sum is σ = 25142472. Its totient is φ = 15879168.

The previous prime is 20400481. The next prime is 20400521. The reversal of 20400505 is 50500402.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 12931216 + 7469289 = 3596^2 + 2733^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 20400505 - 2⁵ = 20400473 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 54952 + ... + 55321.

It is an arithmetic number, because the mean of its divisors is an integer number (3142809).

Almost surely, 2^20400505 is an apocalyptic number.

It is an amenable number.

20400505 is a deficient number, since it is larger than the sum of its proper divisors (4741967).

20400505 is a wasteful number, since it uses less digits than its factorization.

20400505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110315.

The product of its (nonzero) digits is 200, while the sum is 16.

The square root of 20400505 is about 4516.6918203482. The cubic root of 20400505 is about 273.2416962627.

Adding to 20400505 its reverse (50500402), we get a palindrome (70900907).

The spelling of 20400505 in words is "twenty million, four hundred thousand, five hundred five".