21103724 has 12 divisors (see below), whose sum is σ = 37094400. Its totient is φ = 10505328.

The previous prime is 21103723. The next prime is 21103729. The reversal of 21103724 is 42730112.

It is a junction number, because it is equal to n+sod(n) for n = 21103696 and 21103705.

It is not an unprimeable number, because it can be changed into a prime (21103721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10604 + ... + 12435.

It is an arithmetic number, because the mean of its divisors is an integer number (3091200).

Almost surely, 2^21103724 is an apocalyptic number.

It is an amenable number.

21103724 is a deficient number, since it is larger than the sum of its proper divisors (15990676).

21103724 is a wasteful number, since it uses less digits than its factorization.

21103724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23272 (or 23270 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21103724 is about 4593.8789709787. The cubic root of 21103724 is about 276.3459046087.

Adding to 21103724 its reverse (42730112), we get a palindrome (63833836).

The spelling of 21103724 in words is "twenty-one million, one hundred three thousand, seven hundred twenty-four".