21745104 has 20 divisors (see below), whose sum is σ = 56174976. Its totient is φ = 7248352.

The previous prime is 21745081. The next prime is 21745109. The reversal of 21745104 is 40154712.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21745109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 226464 + ... + 226559.

Almost surely, 2^21745104 is an apocalyptic number.

21745104 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21745104 is an abundant number, since it is smaller than the sum of its proper divisors (34429872).

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

21745104 is a wasteful number, since it uses less digits than its factorization.

21745104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 453034 (or 453028 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 24.

The square root of 21745104 is about 4663.1645907045. The cubic root of 21745104 is about 279.1175619975.

Adding to 21745104 its reverse (40154712), we get a palindrome (61899816).

The spelling of 21745104 in words is "twenty-one million, seven hundred forty-five thousand, one hundred four".