21555054440 has 64 divisors (see below), whose sum is σ = 50864837760. Its totient is φ = 8205218560.

The previous prime is 21555054427. The next prime is 21555054467. The reversal of 21555054440 is 4445055512.

It is a super-2 number, since 2×21555054440² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21555054440.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 121775 + ... + 240705.

It is an arithmetic number, because the mean of its divisors is an integer number (794763090).

Almost surely, 2^21555054440 is an apocalyptic number.

21555054440 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 21555054440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25432418880).

21555054440 is an abundant number, since it is smaller than the sum of its proper divisors (29309783320).

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

21555054440 is a wasteful number, since it uses less digits than its factorization.

21555054440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119162 (or 119158 counting only the distinct ones).

The product of its (nonzero) digits is 80000, while the sum is 35.

The spelling of 21555054440 in words is "twenty-one billion, five hundred fifty-five million, fifty-four thousand, four hundred forty".