20381533 has 4 divisors (see below), whose sum is σ = 20394880. Its totient is φ = 20368188.

The previous prime is 20381489. The next prime is 20381549. The reversal of 20381533 is 33518302.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 33518302 = 2 ⋅16759151.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20381533 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20381498 and 20381507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20381573) 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, 4035 + ... + 7552.

It is an arithmetic number, because the mean of its divisors is an integer number (5098720).

Almost surely, 2^20381533 is an apocalyptic number.

It is an amenable number.

20381533 is a deficient number, since it is larger than the sum of its proper divisors (13347).

20381533 is a wasteful number, since it uses less digits than its factorization.

20381533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13346.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 20381533 is about 4514.5911221283. The cubic root of 20381533 is about 273.1569671629.

Adding to 20381533 its reverse (33518302), we get a palindrome (53899835).

The spelling of 20381533 in words is "twenty million, three hundred eighty-one thousand, five hundred thirty-three".