21540186 has 24 divisors (see below), whose sum is σ = 49127520. Its totient is φ = 6802056.

The previous prime is 21540163. The next prime is 21540187. The reversal of 21540186 is 68104512.

It is a super-2 number, since 2×21540186² = 927959225829192, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21540187) 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, 31150 + ... + 31833.

It is an arithmetic number, because the mean of its divisors is an integer number (2046980).

Almost surely, 2^21540186 is an apocalyptic number.

21540186 is an abundant number, since it is smaller than the sum of its proper divisors (27587334).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21540186 is a wasteful number, since it uses less digits than its factorization.

21540186 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63010 (or 63007 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21540186 is about 4641.1405925699. The cubic root of 21540186 is about 278.2380257027.

Adding to 21540186 its reverse (68104512), we get a palindrome (89644698).

It can be divided in two parts, 215 and 40186, that added together give a square (40401 = 201²).

The spelling of 21540186 in words is "twenty-one million, five hundred forty thousand, one hundred eighty-six".