20402505 has 36 divisors (see below), whose sum is σ = 36255492. Its totient is φ = 10612800.

The previous prime is 20402497. The next prime is 20402513. The reversal of 20402505 is 50520402.

It is an interprime number because it is at equal distance from previous prime (20402497) and next prime (20402513).

It can be written as a sum of positive squares in 2 ways, for example, as 14584761 + 5817744 = 3819^2 + 2412^2 .

It is not a de Polignac number, because 20402505 - 2³ = 20402497 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 201955 + ... + 202055.

It is an arithmetic number, because the mean of its divisors is an integer number (1007097).

Almost surely, 2^20402505 is an apocalyptic number.

It is an amenable number.

20402505 is a deficient number, since it is larger than the sum of its proper divisors (15852987).

20402505 is a wasteful number, since it uses less digits than its factorization.

20402505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246 (or 176 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 18.

The square root of 20402505 is about 4516.9132159031. The cubic root of 20402505 is about 273.2506252171.

Adding to 20402505 its reverse (50520402), we get a palindrome (70922907).

The spelling of 20402505 in words is "twenty million, four hundred two thousand, five hundred five".