20402563 has 2 divisors, whose sum is σ = 20402564. Its totient is φ = 20402562.

The previous prime is 20402537. The next prime is 20402579. The reversal of 20402563 is 36520402.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20402563 - 2⁵ = 20402531 is a prime.

It is not a weakly prime, because it can be changed into another prime (20402513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10201281 + 10201282.

It is an arithmetic number, because the mean of its divisors is an integer number (10201282).

Almost surely, 2^20402563 is an apocalyptic number.

20402563 is a deficient number, since it is larger than the sum of its proper divisors (1).

20402563 is an equidigital number, since it uses as much as digits as its factorization.

20402563 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 22.

The square root of 20402563 is about 4516.9196362123. The cubic root of 20402563 is about 273.2508841480.

Adding to 20402563 its reverse (36520402), we get a palindrome (56922965).

The spelling of 20402563 in words is "twenty million, four hundred two thousand, five hundred sixty-three".