7287921 has 8 divisors (see below), whose sum is σ = 10796960. Its totient is φ = 4858596.

The previous prime is 7287919. The next prime is 7287947. The reversal of 7287921 is 1297827.

It is not a de Polignac number, because 7287921 - 2¹ = 7287919 is a prime.

It is a super-2 number, since 2×7287921² = 106227585004482, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (7287911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 134935 + ... + 134988.

It is an arithmetic number, because the mean of its divisors is an integer number (1349620).

Almost surely, 2^7287921 is an apocalyptic number.

It is an amenable number.

7287921 is a deficient number, since it is larger than the sum of its proper divisors (3509039).

7287921 is a wasteful number, since it uses less digits than its factorization.

7287921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 269932 (or 269926 counting only the distinct ones).

The product of its digits is 14112, while the sum is 36.

The square root of 7287921 is about 2699.6149725470. The cubic root of 7287921 is about 193.8806879647.

Subtracting from 7287921 its product of digits (14112), we obtain a square (7273809 = 2697²).

It can be divided in two parts, 72879 and 21, that added together give a square (72900 = 270²).

The spelling of 7287921 in words is "seven million, two hundred eighty-seven thousand, nine hundred twenty-one".