11561321640 has 64 divisors (see below), whose sum is σ = 37837056960. Its totient is φ = 2802744320.

The previous prime is 11561321621. The next prime is 11561321641. The reversal of 11561321640 is 4612316511.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 11561321598 and 11561321607.

It is not an unprimeable number, because it can be changed into a prime (11561321641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4377969 + ... + 4380608.

It is an arithmetic number, because the mean of its divisors is an integer number (591204015).

Almost surely, 2^11561321640 is an apocalyptic number.

11561321640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

11561321640 is an abundant number, since it is smaller than the sum of its proper divisors (26275735320).

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

11561321640 is a wasteful number, since it uses less digits than its factorization.

11561321640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8758602 (or 8758598 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 30.

The spelling of 11561321640 in words is "eleven billion, five hundred sixty-one million, three hundred twenty-one thousand, six hundred forty".