11561571840 has 640 divisors, whose sum is σ = 46329034752. Its totient is φ = 2394685440.

The previous prime is 11561571829. The next prime is 11561571863. The reversal of 11561571840 is 4817516511.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (640).

It is a super-2 number, since 2×11561571840² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 49620364 + ... + 49620596.

Almost surely, 2^11561571840 is an apocalyptic number.

11561571840 is a gapful number since it is divisible by the number (10) 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 11561571840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23164517376).

11561571840 is an abundant number, since it is smaller than the sum of its proper divisors (34767462912).

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

11561571840 is a wasteful number, since it uses less digits than its factorization.

11561571840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350 (or 334 counting only the distinct ones).

The product of its (nonzero) digits is 33600, while the sum is 39.

The spelling of 11561571840 in words is "eleven billion, five hundred sixty-one million, five hundred seventy-one thousand, eight hundred forty".