28763721 has 16 divisors (see below), whose sum is σ = 48700800. Its totient is φ = 16436304.

The previous prime is 28763641. The next prime is 28763723. The reversal of 28763721 is 12736782.

28763721 is a `hidden beast` number, since 287 + 6 + 372 + 1 = 666.

It is not a de Polignac number, because 28763721 - 2¹⁰ = 28762697 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28763723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 75906 + ... + 76283.

It is an arithmetic number, because the mean of its divisors is an integer number (3043800).

Almost surely, 2^28763721 is an apocalyptic number.

28763721 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28763721 is a deficient number, since it is larger than the sum of its proper divisors (19937079).

28763721 is a wasteful number, since it uses less digits than its factorization.

28763721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152205 (or 152199 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 28763721 is about 5363.1819846058. The cubic root of 28763721 is about 306.3950108205.

The spelling of 28763721 in words is "twenty-eight million, seven hundred sixty-three thousand, seven hundred twenty-one".