21345164550 has 120 divisors (see below), whose sum is σ = 60313829400. Its totient is φ = 5595505920.

The previous prime is 21345164549. The next prime is 21345164567. The reversal of 21345164550 is 5546154312.

21345164550 is a `hidden beast` number, since 2 + 1 + 3 + 4 + 5 + 1 + 645 + 5 + 0 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 194286 + ... + 283614.

It is an arithmetic number, because the mean of its divisors is an integer number (502615245).

Almost surely, 2^21345164550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21345164550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30156914700).

21345164550 is an abundant number, since it is smaller than the sum of its proper divisors (38968664850).

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

21345164550 is a wasteful number, since it uses less digits than its factorization.

21345164550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89412 (or 89398 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 36.

The spelling of 21345164550 in words is "twenty-one billion, three hundred forty-five million, one hundred sixty-four thousand, five hundred fifty".