8432721 has 16 divisors (see below), whose sum is σ = 13629120. Its totient is φ = 5110560.

The previous prime is 8432719. The next prime is 8432737. The reversal of 8432721 is 1272348.

8432721 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 8432721 - 2¹ = 8432719 is a prime.

It is a super-2 number, since 2×8432721² = 142221566927682, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an Ulam number.

8432721 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (8432791) 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, 13900 + ... + 14493.

It is an arithmetic number, because the mean of its divisors is an integer number (851820).

Almost surely, 2^8432721 is an apocalyptic number.

It is an amenable number.

8432721 is a deficient number, since it is larger than the sum of its proper divisors (5196399).

8432721 is a wasteful number, since it uses less digits than its factorization.

8432721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28413 (or 28407 counting only the distinct ones).

The product of its digits is 2688, while the sum is 27.

The square root of 8432721 is about 2903.9147714766. The cubic root of 8432721 is about 203.5428778321.

It can be divided in two parts, 84327 and 21, that added together give a palindrome (84348).

The spelling of 8432721 in words is "eight million, four hundred thirty-two thousand, seven hundred twenty-one".