20113531 has 4 divisors (see below), whose sum is σ = 20308912. Its totient is φ = 19918152.

The previous prime is 20113507. The next prime is 20113537. The reversal of 20113531 is 13531102.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20113531 - 2⁷ = 20113403 is a prime.

It is a super-2 number, since 2×20113531² = 809108258575922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20113537) 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, 97536 + ... + 97741.

It is an arithmetic number, because the mean of its divisors is an integer number (5077228).

Almost surely, 2^20113531 is an apocalyptic number.

20113531 is a deficient number, since it is larger than the sum of its proper divisors (195381).

20113531 is a wasteful number, since it uses less digits than its factorization.

20113531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 195380.

The product of its (nonzero) digits is 90, while the sum is 16.

The square root of 20113531 is about 4484.8111442958. The cubic root of 20113531 is about 271.9544104316.

Adding to 20113531 its reverse (13531102), we get a palindrome (33644633).

The spelling of 20113531 in words is "twenty million, one hundred thirteen thousand, five hundred thirty-one".