20406563 has 2 divisors, whose sum is σ = 20406564. Its totient is φ = 20406562.

The previous prime is 20406559. The next prime is 20406611. The reversal of 20406563 is 36560402.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20406563 - 2² = 20406559 is a prime.

It is not a weakly prime, because it can be changed into another prime (20406523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10203281 + 10203282.

It is an arithmetic number, because the mean of its divisors is an integer number (10203282).

Almost surely, 2^20406563 is an apocalyptic number.

20406563 is a deficient number, since it is larger than the sum of its proper divisors (1).

20406563 is an equidigital number, since it uses as much as digits as its factorization.

20406563 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 26.

The square root of 20406563 is about 4517.3623941411. The cubic root of 20406563 is about 273.2687402725.

Adding to 20406563 its reverse (36560402), we get a palindrome (56966965).

The spelling of 20406563 in words is "twenty million, four hundred six thousand, five hundred sixty-three".