999994720650661 has 32 divisors (see below), whose sum is σ = 1047195170380800. Its totient is φ = 954006828203520.

The previous prime is 999994720650649. The next prime is 999994720650721. The reversal of 999994720650661 is 166056027499999.

It is a happy number.

999994720650661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

999994720650661 is a nontrivial binomial coefficient, being equal to C(44721242, 2).

It is a cyclic number.

It is not a de Polignac number, because 999994720650661 - 2¹³ = 999994720642469 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 (999994720650161) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1184691015 + ... + 1185534811.

It is an arithmetic number, because the mean of its divisors is an integer number (32724849074400).

Almost surely, 2^{999994720650661} is an apocalyptic number.

999994720650661 is the 44721241-st triangular number and also the 22360621-st hexagonal number.

999994720650661 is the 14907081-st centered nonagonal number.

It is an amenable number.

999994720650661 is a deficient number, since it is larger than the sum of its proper divisors (47200449730139).

999994720650661 is a wasteful number, since it uses less digits than its factorization.

999994720650661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 845709.

The product of its (nonzero) digits is 3571283520, while the sum is 82.

The spelling of 999994720650661 in words is "nine hundred ninety-nine trillion, nine hundred ninety-four billion, seven hundred twenty million, six hundred fifty thousand, six hundred sixty-one".