61665606643 has 4 divisors (see below), whose sum is σ = 61670533960. Its totient is φ = 61660679328.

The previous prime is 61665606637. The next prime is 61665606671. The reversal of 61665606643 is 34660656616.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 61665606643 - 2¹³ = 61665598451 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61665606943) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2444838 + ... + 2469931.

It is an arithmetic number, because the mean of its divisors is an integer number (15417633490).

Almost surely, 2^61665606643 is an apocalyptic number.

61665606643 is a deficient number, since it is larger than the sum of its proper divisors (4927317).

61665606643 is a wasteful number, since it uses less digits than its factorization.

61665606643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4927316.

The product of its (nonzero) digits is 2799360, while the sum is 49.

The spelling of 61665606643 in words is "sixty-one billion, six hundred sixty-five million, six hundred six thousand, six hundred forty-three".