20531187 has 6 divisors (see below), whose sum is σ = 29656172. Its totient is φ = 13687452.

The previous prime is 20531183. The next prime is 20531213. The reversal of 20531187 is 78113502.

It is not a de Polignac number, because 20531187 - 2² = 20531183 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20531187.

It is not an unprimeable number, because it can be changed into a prime (20531183) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1140613 + ... + 1140630.

Almost surely, 2^20531187 is an apocalyptic number.

20531187 is a deficient number, since it is larger than the sum of its proper divisors (9124985).

20531187 is a wasteful number, since it uses less digits than its factorization.

20531187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2281249 (or 2281246 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 20531187 is about 4531.1352882032. The cubic root of 20531187 is about 273.8239007337.

Adding to 20531187 its reverse (78113502), we get a palindrome (98644689).

It can be divided in two parts, 2053 and 1187, that added together give a triangular number (3240 = T₈₀).

The spelling of 20531187 in words is "twenty million, five hundred thirty-one thousand, one hundred eighty-seven".