21831418 has 16 divisors (see below), whose sum is σ = 39395520. Its totient is φ = 8863776.

The previous prime is 21831373. The next prime is 21831419. The reversal of 21831418 is 81413812.

It is a super-2 number, since 2×21831418² = 953221623781448, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21831419) 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, 40771 + ... + 41302.

It is an arithmetic number, because the mean of its divisors is an integer number (2462220).

Almost surely, 2^21831418 is an apocalyptic number.

21831418 is a deficient number, since it is larger than the sum of its proper divisors (17564102).

21831418 is a wasteful number, since it uses less digits than its factorization.

21831418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82101.

The product of its digits is 1536, while the sum is 28.

The square root of 21831418 is about 4672.4102987644. The cubic root of 21831418 is about 279.4863798416.

The spelling of 21831418 in words is "twenty-one million, eight hundred thirty-one thousand, four hundred eighteen".