261646064624440 has 128 divisors (see below), whose sum is σ = 609491455372800. Its totient is φ = 101009114519040.

The previous prime is 261646064624339. The next prime is 261646064624473. The reversal of 261646064624440 is 44426460646162.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 453196837 + ... + 453773803.

It is an arithmetic number, because the mean of its divisors is an integer number (4761651995100).

Almost surely, 2^{261646064624440} is an apocalyptic number.

261646064624440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261646064624440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (304745727686400).

261646064624440 is an abundant number, since it is smaller than the sum of its proper divisors (347845390748360).

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

261646064624440 is a wasteful number, since it uses less digits than its factorization.

261646064624440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 579485 (or 579481 counting only the distinct ones).

The product of its (nonzero) digits is 31850496, while the sum is 55.

The spelling of 261646064624440 in words is "two hundred sixty-one trillion, six hundred forty-six billion, sixty-four million, six hundred twenty-four thousand, four hundred forty".