66561636450 has 24 divisors (see below), whose sum is σ = 165072858768. Its totient is φ = 17749769680.

The previous prime is 66561636433. The next prime is 66561636461. The reversal of 66561636450 is 5463616566.

It is a self number, because there is not a number n which added to its sum of digits gives 66561636450.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 221871972 + ... + 221872271.

It is an arithmetic number, because the mean of its divisors is an integer number (6878035782).

Almost surely, 2^66561636450 is an apocalyptic number.

66561636450 is an abundant number, since it is smaller than the sum of its proper divisors (98511222318).

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

66561636450 is a wasteful number, since it uses less digits than its factorization.

66561636450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 443744258 (or 443744253 counting only the distinct ones).

The product of its (nonzero) digits is 2332800, while the sum is 48.

The spelling of 66561636450 in words is "sixty-six billion, five hundred sixty-one million, six hundred thirty-six thousand, four hundred fifty".