7666564621 has 4 divisors (see below), whose sum is σ = 7853554044. Its totient is φ = 7479575200.

The previous prime is 7666564603. The next prime is 7666564649. The reversal of 7666564621 is 1264656667.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1264656667 = 1163 ⋅1087409.

It can be written as a sum of positive squares in 2 ways, for example, as 820822500 + 6845742121 = 28650^2 + 82739^2 .

It is a cyclic number.

It is not a de Polignac number, because 7666564621 - 2²¹ = 7664467469 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7666564651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 93494650 + ... + 93494731.

It is an arithmetic number, because the mean of its divisors is an integer number (1963388511).

Almost surely, 2^7666564621 is an apocalyptic number.

It is an amenable number.

7666564621 is a deficient number, since it is larger than the sum of its proper divisors (186989423).

7666564621 is a wasteful number, since it uses less digits than its factorization.

7666564621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186989422.

The product of its digits is 2177280, while the sum is 49.

The square root of 7666564621 is about 87558.9208533317. The cubic root of 7666564621 is about 1971.8184846546.

The spelling of 7666564621 in words is "seven billion, six hundred sixty-six million, five hundred sixty-four thousand, six hundred twenty-one".