21545613708 has 144 divisors (see below), whose sum is σ = 53671871232. Its totient is φ = 6719328000.

The previous prime is 21545613631. The next prime is 21545613709. The reversal of 21545613708 is 80731654512.

It is a happy number.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21545613708.

It is not an unprimeable number, because it can be changed into a prime (21545613709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 213322858 + ... + 213322958.

It is an arithmetic number, because the mean of its divisors is an integer number (372721328).

Almost surely, 2^21545613708 is an apocalyptic number.

It is an amenable number.

21545613708 is an abundant number, since it is smaller than the sum of its proper divisors (32126257524).

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

21545613708 is a wasteful number, since it uses less digits than its factorization.

21545613708 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 384 (or 281 counting only the distinct ones).

The product of its (nonzero) digits is 201600, while the sum is 42.

The spelling of 21545613708 in words is "twenty-one billion, five hundred forty-five million, six hundred thirteen thousand, seven hundred eight".