21281921040 has 80 divisors (see below), whose sum is σ = 67218787008. Its totient is φ = 5568096768.

The previous prime is 21281921039. The next prime is 21281921077. The reversal of 21281921040 is 4012918212.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21281920989 and 21281921007.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 823834 + ... + 849273.

Almost surely, 2^21281921040 is an apocalyptic number.

21281921040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21281921040 is an abundant number, since it is smaller than the sum of its proper divisors (45936865968).

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

21281921040 is a wasteful number, since it uses less digits than its factorization.

21281921040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1673176 (or 1673170 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The spelling of 21281921040 in words is "twenty-one billion, two hundred eighty-one million, nine hundred twenty-one thousand, forty".