28103721 has 8 divisors (see below), whose sum is σ = 37618464. Its totient is φ = 18662400.

The previous prime is 28103711. The next prime is 28103729. The reversal of 28103721 is 12730182.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28103721 - 2¹¹ = 28101673 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 28103691 and 28103700.

It is not an unprimeable number, because it can be changed into a prime (28103729) 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, 17455 + ... + 18996.

It is an arithmetic number, because the mean of its divisors is an integer number (4702308).

Almost surely, 2^28103721 is an apocalyptic number.

It is an amenable number.

28103721 is a deficient number, since it is larger than the sum of its proper divisors (9514743).

28103721 is a wasteful number, since it uses less digits than its factorization.

28103721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36711.

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 28103721 is about 5301.2942759292. The cubic root of 28103721 is about 304.0333852128.

The spelling of 28103721 in words is "twenty-eight million, one hundred three thousand, seven hundred twenty-one".