21380186 has 16 divisors (see below), whose sum is σ = 34058880. Its totient is φ = 10031040.

The previous prime is 21380171. The next prime is 21380189. The reversal of 21380186 is 68108312.

It is a super-2 number, since 2×21380186² = 914224706789192, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21380189) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13925 + ... + 15383.

It is an arithmetic number, because the mean of its divisors is an integer number (2128680).

Almost surely, 2^21380186 is an apocalyptic number.

21380186 is a deficient number, since it is larger than the sum of its proper divisors (12678694).

21380186 is a wasteful number, since it uses less digits than its factorization.

21380186 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1909.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 21380186 is about 4623.8713217390. The cubic root of 21380186 is about 277.5473976881.

Adding to 21380186 its reverse (68108312), we get a palindrome (89488498).

The spelling of 21380186 in words is "twenty-one million, three hundred eighty thousand, one hundred eighty-six".