1261642604544 has 420 divisors, whose sum is σ = 4384601753004. Its totient is φ = 360460025856.

The previous prime is 1261642604543. The next prime is 1261642604549. The reversal of 1261642604544 is 4454062461621.

1261642604544 is a `hidden beast` number, since 1 + 2 + 6 + 1 + 6 + 42 + 60 + 4 + 544 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 1261642604544.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261642604543) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 32494647 + ... + 32533449.

Almost surely, 2^{1261642604544} is an apocalyptic number.

1261642604544 is a gapful number since it is divisible by the number (14) 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 1261642604544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2192300876502).

1261642604544 is an abundant number, since it is smaller than the sum of its proper divisors (3122959148460).

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

1261642604544 is an frugal number, since it uses more digits than its factorization.

1261642604544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38855 (or 38815 counting only the distinct ones).

The product of its (nonzero) digits is 1105920, while the sum is 45.

The spelling of 1261642604544 in words is "one trillion, two hundred sixty-one billion, six hundred forty-two million, six hundred four thousand, five hundred forty-four".