21186131 has 4 divisors (see below), whose sum is σ = 22432392. Its totient is φ = 19939872.

The previous prime is 21186127. The next prime is 21186149. The reversal of 21186131 is 13168112.

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 21186131 - 2² = 21186127 is a prime.

It is a super-2 number, since 2×21186131² = 897704293498322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21186097 and 21186106.

It is not an unprimeable number, because it can be changed into a prime (21186181) 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, 623105 + ... + 623138.

It is an arithmetic number, because the mean of its divisors is an integer number (5608098).

Almost surely, 2^21186131 is an apocalyptic number.

21186131 is a deficient number, since it is larger than the sum of its proper divisors (1246261).

21186131 is a wasteful number, since it uses less digits than its factorization.

21186131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1246260.

The product of its digits is 288, while the sum is 23.

The square root of 21186131 is about 4602.8394497310. The cubic root of 21186131 is about 276.7051344070.

The spelling of 21186131 in words is "twenty-one million, one hundred eighty-six thousand, one hundred thirty-one".