21630521550 has 48 divisors (see below), whose sum is σ = 58520397312. Its totient is φ = 5243762400.

The previous prime is 21630521461. The next prime is 21630521551. The reversal of 21630521550 is 5512503612.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21630521551) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6553054 + ... + 6556353.

It is an arithmetic number, because the mean of its divisors is an integer number (1219174944).

Almost surely, 2^21630521550 is an apocalyptic number.

21630521550 is an abundant number, since it is smaller than the sum of its proper divisors (36889875762).

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

21630521550 is a wasteful number, since it uses less digits than its factorization.

21630521550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13109433 (or 13109428 counting only the distinct ones).

The product of its (nonzero) digits is 9000, while the sum is 30.

The spelling of 21630521550 in words is "twenty-one billion, six hundred thirty million, five hundred twenty-one thousand, five hundred fifty".