20513423 has 4 divisors (see below), whose sum is σ = 23443920. Its totient is φ = 17582928.

The previous prime is 20513419. The next prime is 20513431. The reversal of 20513423 is 32431502.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32431502 = 2 ⋅16215751.

It is a cyclic number.

It is not a de Polignac number, because 20513423 - 2² = 20513419 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20513395 and 20513404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20513443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1465238 + ... + 1465251.

It is an arithmetic number, because the mean of its divisors is an integer number (5860980).

Almost surely, 2^20513423 is an apocalyptic number.

20513423 is a deficient number, since it is larger than the sum of its proper divisors (2930497).

20513423 is an equidigital number, since it uses as much as digits as its factorization.

20513423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2930496.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 20513423 is about 4529.1746488737. The cubic root of 20513423 is about 273.7449052797.

Adding to 20513423 its reverse (32431502), we get a palindrome (52944925).

The spelling of 20513423 in words is "twenty million, five hundred thirteen thousand, four hundred twenty-three".