21661150544 has 80 divisors (see below), whose sum is σ = 46099293504. Its totient is φ = 9778406400.

The previous prime is 21661150523. The next prime is 21661150547. The reversal of 21661150544 is 44505116612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661150547) 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, 20968652 + ... + 20969684.

Almost surely, 2^21661150544 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21661150544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23049646752).

21661150544 is an abundant number, since it is smaller than the sum of its proper divisors (24438142960).

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

21661150544 is a wasteful number, since it uses less digits than its factorization.

21661150544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1756 (or 1750 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 35.

The spelling of 21661150544 in words is "twenty-one billion, six hundred sixty-one million, one hundred fifty thousand, five hundred forty-four".