661426365040 has 40 divisors (see below), whose sum is σ = 1757504342880. Its totient is φ = 226774753536.

The previous prime is 661426365023. The next prime is 661426365053. The reversal of 661426365040 is 40563624166.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 590558695 + ... + 590559814.

It is an arithmetic number, because the mean of its divisors is an integer number (43937608572).

Almost surely, 2^661426365040 is an apocalyptic number.

It is an amenable number.

661426365040 is an abundant number, since it is smaller than the sum of its proper divisors (1096077977840).

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

661426365040 is a wasteful number, since it uses less digits than its factorization.

661426365040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1181118529 (or 1181118523 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 43.

The spelling of 661426365040 in words is "six hundred sixty-one billion, four hundred twenty-six million, three hundred sixty-five thousand, forty".