20402 has 6 divisors (see below), whose sum is σ = 30909. Its totient is φ = 10100.

The previous prime is 20399. The next prime is 20407.

Added to its reverse (20402) it gives a square (40804 = 202²).

20402 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in 2 ways, for example, as 14161 + 6241 = 119^2 + 79^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=101.

It is a Duffinian number.

It is a nialpdrome in base 12.

It is a self number, because there is not a number n which added to its sum of digits gives 20402.

It is not an unprimeable number, because it can be changed into a prime (20407) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 152 + ... + 252.

2²⁰⁴⁰² is an apocalyptic number.

20402 is a deficient number, since it is larger than the sum of its proper divisors (10507).

20402 is an equidigital number, since it uses as much as digits as its factorization.

20402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204 (or 103 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 8.

The square root of 20402 is about 142.8355697997. The cubic root of 20402 is about 27.3248370711.

The spelling of 20402 in words is "twenty thousand, four hundred two", and thus it is an iban number.