21381418 has 16 divisors (see below), whose sum is σ = 33022080. Its totient is φ = 10376800.

The previous prime is 21381407. The next prime is 21381433. The reversal of 21381418 is 81418312.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19053 + ... + 20143.

It is an arithmetic number, because the mean of its divisors is an integer number (2063880).

Almost surely, 2^21381418 is an apocalyptic number.

21381418 is a deficient number, since it is larger than the sum of its proper divisors (11640662).

21381418 is a wasteful number, since it uses less digits than its factorization.

21381418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1373.

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

The square root of 21381418 is about 4624.0045415203. The cubic root of 21381418 is about 277.5527286649.

The spelling of 21381418 in words is "twenty-one million, three hundred eighty-one thousand, four hundred eighteen".