21056717040 has 40 divisors (see below), whose sum is σ = 65275823568. Its totient is φ = 5615124480.

The previous prime is 21056717027. The next prime is 21056717081. The reversal of 21056717040 is 4071765012.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 21056716992 and 21056717010.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43867921 + ... + 43868400.

Almost surely, 2^21056717040 is an apocalyptic number.

21056717040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21056717040 is an abundant number, since it is smaller than the sum of its proper divisors (44219106528).

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

21056717040 is a wasteful number, since it uses less digits than its factorization.

21056717040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87736337 (or 87736331 counting only the distinct ones).

The product of its (nonzero) digits is 11760, while the sum is 33.

The spelling of 21056717040 in words is "twenty-one billion, fifty-six million, seven hundred seventeen thousand, forty".