66528820621 has 8 divisors (see below), whose sum is σ = 68484712184. Its totient is φ = 64581235200.

The previous prime is 66528820619. The next prime is 66528820649. The reversal of 66528820621 is 12602882566.

It can be written as a sum of positive squares in 4 ways, for example, as 60762025 + 66468058596 = 7795^2 + 257814^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66528820621 - 2¹ = 66528820619 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 (66528826621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2060280 + ... + 2092321.

It is an arithmetic number, because the mean of its divisors is an integer number (8560589023).

Almost surely, 2^66528820621 is an apocalyptic number.

It is an amenable number.

66528820621 is a deficient number, since it is larger than the sum of its proper divisors (1955891563).

66528820621 is a wasteful number, since it uses less digits than its factorization.

66528820621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4153071.

The product of its (nonzero) digits is 552960, while the sum is 46.

The spelling of 66528820621 in words is "sixty-six billion, five hundred twenty-eight million, eight hundred twenty thousand, six hundred twenty-one".