21100724 has 12 divisors (see below), whose sum is σ = 37048704. Its totient is φ = 10515384.

The previous prime is 21100711. The next prime is 21100727. The reversal of 21100724 is 42700112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100727) 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, 7364 + ... + 9819.

It is an arithmetic number, because the mean of its divisors is an integer number (3087392).

Almost surely, 2^21100724 is an apocalyptic number.

It is an amenable number.

21100724 is a deficient number, since it is larger than the sum of its proper divisors (15947980).

21100724 is a wasteful number, since it uses less digits than its factorization.

21100724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17494 (or 17492 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 17.

The square root of 21100724 is about 4593.5524379286. The cubic root of 21100724 is about 276.3328093370.

Adding to 21100724 its reverse (42700112), we get a palindrome (63800836).

The spelling of 21100724 in words is "twenty-one million, one hundred thousand, seven hundred twenty-four".