7563721 has 16 divisors (see below), whose sum is σ = 8741376. Its totient is φ = 6480000.

The previous prime is 7563719. The next prime is 7563761. The reversal of 7563721 is 1273657.

7563721 = T₆₈₃ + T₆₈₄ + ... + T₇₁₃.

It is a 4-Lehmer number, since φ(7563721) divides (7563721-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 7563721 - 2¹ = 7563719 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

7563721 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (7563761) 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 15 ways as a sum of consecutive naturals, for example, 13711 + ... + 14251.

It is an arithmetic number, because the mean of its divisors is an integer number (546336).

Almost surely, 2^7563721 is an apocalyptic number.

It is an amenable number.

7563721 is a deficient number, since it is larger than the sum of its proper divisors (1177655).

7563721 is a wasteful number, since it uses less digits than its factorization.

7563721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 624.

The product of its digits is 8820, while the sum is 31.

The square root of 7563721 is about 2750.2219910400. The cubic root of 7563721 is about 196.2961734297.

Subtracting from 7563721 its reverse (1273657), we obtain a square (6290064 = 2508²).

The spelling of 7563721 in words is "seven million, five hundred sixty-three thousand, seven hundred twenty-one".