7881521 has 2 divisors, whose sum is σ = 7881522. Its totient is φ = 7881520.

The previous prime is 7881509. The next prime is 7881527. The reversal of 7881521 is 1251887.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5664400 + 2217121 = 2380^2 + 1489^2 .

It is a cyclic number.

It is not a de Polignac number, because 7881521 - 2¹⁸ = 7619377 is a prime.

It is not a weakly prime, because it can be changed into another prime (7881527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3940760 + 3940761.

It is an arithmetic number, because the mean of its divisors is an integer number (3940761).

Almost surely, 2^7881521 is an apocalyptic number.

It is an amenable number.

7881521 is a deficient number, since it is larger than the sum of its proper divisors (1).

7881521 is an equidigital number, since it uses as much as digits as its factorization.

7881521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4480, while the sum is 32.

The square root of 7881521 is about 2807.4046733594. The cubic root of 7881521 is about 199.0077604441.

The spelling of 7881521 in words is "seven million, eight hundred eighty-one thousand, five hundred twenty-one".