21649952550 has 24 divisors (see below), whose sum is σ = 53691882696. Its totient is φ = 5773320640.

The previous prime is 21649952549. The next prime is 21649952551. The reversal of 21649952550 is 5525994612.

It is an interprime number because it is at equal distance from previous prime (21649952549) and next prime (21649952551).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21649952550.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21649952551) 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, 72166359 + ... + 72166658.

It is an arithmetic number, because the mean of its divisors is an integer number (2237161779).

Almost surely, 2^21649952550 is an apocalyptic number.

21649952550 is an abundant number, since it is smaller than the sum of its proper divisors (32041930146).

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

21649952550 is a wasteful number, since it uses less digits than its factorization.

21649952550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144333032 (or 144333027 counting only the distinct ones).

The product of its (nonzero) digits is 972000, while the sum is 48.

The spelling of 21649952550 in words is "twenty-one billion, six hundred forty-nine million, nine hundred fifty-two thousand, five hundred fifty".