7721665 has 12 divisors (see below), whose sum is σ = 10779156. Its totient is φ = 5294688.

The previous prime is 7721611. The next prime is 7721671. The reversal of 7721665 is 5661277.

It can be written as a sum of positive squares in 2 ways, for example, as 1787569 + 5934096 = 1337^2 + 2436^2 .

It is not a de Polignac number, because 7721665 - 2¹⁷ = 7590593 is a prime.

It is a super-2 number, since 2×7721665² = 119248220744450, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 7721665.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15514 + ... + 16003.

It is an arithmetic number, because the mean of its divisors is an integer number (898263).

Almost surely, 2^7721665 is an apocalyptic number.

It is an amenable number.

7721665 is a deficient number, since it is larger than the sum of its proper divisors (3057491).

7721665 is a wasteful number, since it uses less digits than its factorization.

7721665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31536 (or 31529 counting only the distinct ones).

The product of its digits is 17640, while the sum is 34.

The square root of 7721665 is about 2778.7884050427. The cubic root of 7721665 is about 197.6531099216.

The spelling of 7721665 in words is "seven million, seven hundred twenty-one thousand, six hundred sixty-five".