642644460661 has 16 divisors (see below), whose sum is σ = 811464839424. Its totient is φ = 495895175424.

The previous prime is 642644460649. The next prime is 642644460671. The reversal of 642644460661 is 166064446246.

It is a cyclic number.

It is not a de Polignac number, because 642644460661 - 2⁵ = 642644460629 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 (642644460671) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 117396690 + ... + 117402163.

It is an arithmetic number, because the mean of its divisors is an integer number (50716552464).

Almost surely, 2^642644460661 is an apocalyptic number.

It is an amenable number.

642644460661 is a deficient number, since it is larger than the sum of its proper divisors (168820378763).

642644460661 is a wasteful number, since it uses less digits than its factorization.

642644460661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 234798900.

The product of its (nonzero) digits is 3981312, while the sum is 49.

The spelling of 642644460661 in words is "six hundred forty-two billion, six hundred forty-four million, four hundred sixty thousand, six hundred sixty-one".