20351563 has 4 divisors (see below), whose sum is σ = 20360680. Its totient is φ = 20342448.

The previous prime is 20351537. The next prime is 20351579. The reversal of 20351563 is 36515302.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a 4-Lehmer number, since φ(20351563) divides (20351563-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 20351563 - 2¹³ = 20343371 is a prime.

It is a super-2 number, since 2×20351563² = 828372233085938, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20351503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1303 + ... + 6511.

It is an arithmetic number, because the mean of its divisors is an integer number (5090170).

Almost surely, 2^20351563 is an apocalyptic number.

20351563 is a deficient number, since it is larger than the sum of its proper divisors (9117).

20351563 is an equidigital number, since it uses as much as digits as its factorization.

20351563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9116.

The product of its (nonzero) digits is 2700, while the sum is 25.

The square root of 20351563 is about 4511.2706635714. The cubic root of 20351563 is about 273.0230137093.

Adding to 20351563 its reverse (36515302), we get a palindrome (56866865).

The spelling of 20351563 in words is "twenty million, three hundred fifty-one thousand, five hundred sixty-three".