21186361 has 16 divisors (see below), whose sum is σ = 25297920. Its totient is φ = 17360640.

The previous prime is 21186359. The next prime is 21186367. The reversal of 21186361 is 16368112.

It is a cyclic number.

It is not a de Polignac number, because 21186361 - 2¹ = 21186359 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21186367) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18765 + ... + 19861.

It is an arithmetic number, because the mean of its divisors is an integer number (1581120).

Almost surely, 2^21186361 is an apocalyptic number.

It is an amenable number.

21186361 is a deficient number, since it is larger than the sum of its proper divisors (4111559).

21186361 is a wasteful number, since it uses less digits than its factorization.

21186361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1224.

The product of its digits is 1728, while the sum is 28.

The square root of 21186361 is about 4602.8644342409. The cubic root of 21186361 is about 276.7061357217.

The spelling of 21186361 in words is "twenty-one million, one hundred eighty-six thousand, three hundred sixty-one".