21181416 has 32 divisors (see below), whose sum is σ = 53071200. Its totient is φ = 7044800.

The previous prime is 21181411. The next prime is 21181423. The reversal of 21181416 is 61418112.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (21181411) 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, 16195 + ... + 17453.

It is an arithmetic number, because the mean of its divisors is an integer number (1658475).

Almost surely, 2^21181416 is an apocalyptic number.

It is an amenable number.

21181416 is an abundant number, since it is smaller than the sum of its proper divisors (31889784).

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

21181416 is a wasteful number, since it uses less digits than its factorization.

21181416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1969 (or 1965 counting only the distinct ones).

The product of its digits is 384, while the sum is 24.

The square root of 21181416 is about 4602.3272373876. The cubic root of 21181416 is about 276.6846058593.

Adding to 21181416 its reverse (61418112), we get a palindrome (82599528).

The spelling of 21181416 in words is "twenty-one million, one hundred eighty-one thousand, four hundred sixteen".