21555041440 has 24 divisors (see below), whose sum is σ = 50923785780. Its totient is φ = 8622016512.

The previous prime is 21555041429. The next prime is 21555041467. The reversal of 21555041440 is 4414055512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20750978704 + 804062736 = 144052^2 + 28356^2 .

It is a super-2 number, since 2×21555041440² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67359345 + ... + 67359664.

Almost surely, 2^21555041440 is an apocalyptic number.

21555041440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21555041440 is an abundant number, since it is smaller than the sum of its proper divisors (29368744340).

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

21555041440 is a wasteful number, since it uses less digits than its factorization.

21555041440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134719024 (or 134719016 counting only the distinct ones).

The product of its (nonzero) digits is 16000, while the sum is 31.

Adding to 21555041440 its reverse (4414055512), we get a palindrome (25969096952).

The spelling of 21555041440 in words is "twenty-one billion, five hundred fifty-five million, forty-one thousand, four hundred forty".