7721540 has 24 divisors (see below), whose sum is σ = 16775640. Its totient is φ = 2981888.

The previous prime is 7721521. The next prime is 7721611. The reversal of 7721540 is 451277.

It can be written as a sum of positive squares in 4 ways, for example, as 506944 + 7214596 = 712^2 + 2686^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6077 + ... + 7236.

It is an arithmetic number, because the mean of its divisors is an integer number (698985).

Almost surely, 2^7721540 is an apocalyptic number.

It is an amenable number.

7721540 is an abundant number, since it is smaller than the sum of its proper divisors (9054100).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

7721540 is a wasteful number, since it uses less digits than its factorization.

7721540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13351 (or 13349 counting only the distinct ones).

The product of its (nonzero) digits is 1960, while the sum is 26.

The square root of 7721540 is about 2778.7659131348. The cubic root of 7721540 is about 197.6520433653.

The spelling of 7721540 in words is "seven million, seven hundred twenty-one thousand, five hundred forty".