21361131 has 32 divisors (see below), whose sum is σ = 35043840. Its totient is φ = 12751200.

The previous prime is 21361121. The next prime is 21361133. The reversal of 21361131 is 13116312.

21361131 is a `hidden beast` number, since 21 + 3 + 611 + 31 = 666.

It is not a de Polignac number, because 21361131 - 2⁷ = 21361003 is a prime.

It is a super-2 number, since 2×21361131² = 912595835198322, which contains 22 as substring.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21361133) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 20581 + ... + 21593.

It is an arithmetic number, because the mean of its divisors is an integer number (1095120).

Almost surely, 2^21361131 is an apocalyptic number.

21361131 is a deficient number, since it is larger than the sum of its proper divisors (13682709).

21361131 is a wasteful number, since it uses less digits than its factorization.

21361131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1104 (or 1098 counting only the distinct ones).

The product of its digits is 108, while the sum is 18.

The square root of 21361131 is about 4621.8103595885. The cubic root of 21361131 is about 277.4649188670.

Adding to 21361131 its reverse (13116312), we get a palindrome (34477443).

The spelling of 21361131 in words is "twenty-one million, three hundred sixty-one thousand, one hundred thirty-one".