21161187 has 12 divisors (see below), whose sum is σ = 30745104. Its totient is φ = 14024880.

The previous prime is 21161137. The next prime is 21161191. The reversal of 21161187 is 78116112.

It is not a de Polignac number, because 21161187 - 2⁷ = 21161059 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21161187.

It is not an unprimeable number, because it can be changed into a prime (21161137) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5239 + ... + 8352.

It is an arithmetic number, because the mean of its divisors is an integer number (2562092).

Almost surely, 2^21161187 is an apocalyptic number.

21161187 is a deficient number, since it is larger than the sum of its proper divisors (9583917).

21161187 is a wasteful number, since it uses less digits than its factorization.

21161187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13770 (or 13767 counting only the distinct ones).

The product of its digits is 672, while the sum is 27.

The square root of 21161187 is about 4600.1290199298. The cubic root of 21161187 is about 276.5964966156.

Adding to 21161187 its reverse (78116112), we get a palindrome (99277299).

The spelling of 21161187 in words is "twenty-one million, one hundred sixty-one thousand, one hundred eighty-seven".