21651069440 has 960 divisors, whose sum is σ = 76175624448. Its totient is φ = 5780275200.

The previous prime is 21651069439. The next prime is 21651069469. The reversal of 21651069440 is 4496015612.

It is a junction number, because it is equal to n+sod(n) for n = 21651069394 and 21651069403.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 304944605 + ... + 304944675.

Almost surely, 2^21651069440 is an apocalyptic number.

21651069440 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 21651069440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38087812224).

21651069440 is an abundant number, since it is smaller than the sum of its proper divisors (54524555008).

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

21651069440 is a wasteful number, since it uses less digits than its factorization.

21651069440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149 (or 126 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 38.

The spelling of 21651069440 in words is "twenty-one billion, six hundred fifty-one million, sixty-nine thousand, four hundred forty".