21508369740 has 864 divisors, whose sum is σ = 86329152000. Its totient is φ = 4269957120.

The previous prime is 21508369679. The next prime is 21508369763. The reversal of 21508369740 is 4796380512.

21508369740 is a `hidden beast` number, since 21 + 508 + 36 + 97 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 108082161 + ... + 108082359.

It is an arithmetic number, because the mean of its divisors is an integer number (99918000).

It is a 1-persistent number, because it is pandigital, but 2⋅21508369740 = 43016739480 is not.

Almost surely, 2^21508369740 is an apocalyptic number.

21508369740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21508369740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43164576000).

21508369740 is an abundant number, since it is smaller than the sum of its proper divisors (64820782260).

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

21508369740 is a wasteful number, since it uses less digits than its factorization.

21508369740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 287 (or 269 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The spelling of 21508369740 in words is "twenty-one billion, five hundred eight million, three hundred sixty-nine thousand, seven hundred forty".