21065550550 has 24 divisors (see below), whose sum is σ = 42743918232. Its totient is φ = 7660200000.

The previous prime is 21065550547. The next prime is 21065550557. The reversal of 21065550550 is 5505556012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21065550557) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19149951 + ... + 19151050.

It is an arithmetic number, because the mean of its divisors is an integer number (1780996593).

Almost surely, 2^21065550550 is an apocalyptic number.

21065550550 is an abundant number, since it is smaller than the sum of its proper divisors (21678367682).

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

21065550550 is a wasteful number, since it uses less digits than its factorization.

21065550550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38301024 (or 38301019 counting only the distinct ones).

The product of its (nonzero) digits is 37500, while the sum is 34.

The spelling of 21065550550 in words is "twenty-one billion, sixty-five million, five hundred fifty thousand, five hundred fifty".