21021550506 has 48 divisors (see below), whose sum is σ = 49808977920. Its totient is φ = 6354567360.

The previous prime is 21021550499. The next prime is 21021550507. The reversal of 21021550506 is 60505512012.

21021550506 is a `hidden beast` number, since 2 + 1 + 0 + 2 + 155 + 0 + 506 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21021550506.

It is not an unprimeable number, because it can be changed into a prime (21021550507) 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, 48810 + ... + 210773.

It is an arithmetic number, because the mean of its divisors is an integer number (1037687040).

Almost surely, 2^21021550506 is an apocalyptic number.

21021550506 is an abundant number, since it is smaller than the sum of its proper divisors (28787427414).

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

21021550506 is a wasteful number, since it uses less digits than its factorization.

21021550506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260011 (or 260008 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

The spelling of 21021550506 in words is "twenty-one billion, twenty-one million, five hundred fifty thousand, five hundred six".