20135231 has 4 divisors (see below), whose sum is σ = 21195000. Its totient is φ = 19075464.

The previous prime is 20135221. The next prime is 20135239. The reversal of 20135231 is 13253102.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13253102 = 2 ⋅6626551.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20135231 is a prime.

It is a super-2 number, since 2×20135231² = 810855054846722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20135239) 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, 529856 + ... + 529893.

It is an arithmetic number, because the mean of its divisors is an integer number (5298750).

Almost surely, 2^20135231 is an apocalyptic number.

20135231 is a deficient number, since it is larger than the sum of its proper divisors (1059769).

20135231 is a wasteful number, since it uses less digits than its factorization.

20135231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1059768.

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 20135231 is about 4487.2297690223. The cubic root of 20135231 is about 272.0521769498.

Adding to 20135231 its reverse (13253102), we get a palindrome (33388333).

The spelling of 20135231 in words is "twenty million, one hundred thirty-five thousand, two hundred thirty-one".