21244636440 has 96 divisors (see below), whose sum is σ = 72679042800. Its totient is φ = 5367064320.

The previous prime is 21244636423. The next prime is 21244636463. The reversal of 21244636440 is 4463644212.

21244636440 is a `hidden beast` number, since 2 + 1 + 2 + 4 + 4 + 6 + 3 + 644 + 0 = 666.

It is a super-3 number, since 3×21244636440³ (a number of 32 digits) contains 333 as substring.

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 = 21244636395 and 21244636404.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1546131 + ... + 1559810.

Almost surely, 2^21244636440 is an apocalyptic number.

21244636440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21244636440 is an abundant number, since it is smaller than the sum of its proper divisors (51434406360).

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

21244636440 is a wasteful number, since it uses less digits than its factorization.

21244636440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3105977 (or 3105970 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 36.

The spelling of 21244636440 in words is "twenty-one billion, two hundred forty-four million, six hundred thirty-six thousand, four hundred forty".