21029617440 has 384 divisors, whose sum is σ = 83931966720. Its totient is φ = 4871798784.

The previous prime is 21029617421. The next prime is 21029617471. The reversal of 21029617440 is 4471692012.

It is a happy number.

21029617440 is a `hidden beast` number, since 2 + 10 + 29 + 617 + 4 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21029617395 and 21029617404.

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 63 ways as a sum of consecutive naturals, for example, 943707 + ... + 965733.

It is an arithmetic number, because the mean of its divisors is an integer number (218572830).

Almost surely, 2^21029617440 is an apocalyptic number.

21029617440 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 21029617440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41965983360).

21029617440 is an abundant number, since it is smaller than the sum of its proper divisors (62902349280).

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

21029617440 is a wasteful number, since it uses less digits than its factorization.

21029617440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22081 (or 22067 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The spelling of 21029617440 in words is "twenty-one billion, twenty-nine million, six hundred seventeen thousand, four hundred forty".