21021043012040 has 16 divisors (see below), whose sum is σ = 47297346777180. Its totient is φ = 8408417204800.

The previous prime is 21021043012007. The next prime is 21021043012043. The reversal of 21021043012040 is 4021034012012.

It can be written as a sum of positive squares in 2 ways, for example, as 20324822989636 + 696220022404 = 4508306^2 + 834398^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (21021043012043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 262763037611 + ... + 262763037690.

Almost surely, 2^{21021043012040} is an apocalyptic number.

21021043012040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021043012040 is an abundant number, since it is smaller than the sum of its proper divisors (26276303765140).

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

21021043012040 is a wasteful number, since it uses less digits than its factorization.

21021043012040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 525526075312 (or 525526075308 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

Adding to 21021043012040 its reverse (4021034012012), we get a palindrome (25042077024052).

The spelling of 21021043012040 in words is "twenty-one trillion, twenty-one billion, forty-three million, twelve thousand, forty".