21402721540 has 36 divisors (see below), whose sum is σ = 47745115236. Its totient is φ = 8057492992.

The previous prime is 21402721537. The next prime is 21402721541. The reversal of 21402721540 is 4512720412.

It can be written as a sum of positive squares in 6 ways, for example, as 4077844164 + 17324877376 = 63858^2 + 131624^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21402721499 and 21402721508.

It is not an unprimeable number, because it can be changed into a prime (21402721541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1845667 + ... + 1857226.

It is an arithmetic number, because the mean of its divisors is an integer number (1326253201).

Almost surely, 2^21402721540 is an apocalyptic number.

21402721540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21402721540 is an abundant number, since it is smaller than the sum of its proper divisors (26342393696).

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

21402721540 is a wasteful number, since it uses less digits than its factorization.

21402721540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3702936 (or 3702917 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 28.

The spelling of 21402721540 in words is "twenty-one billion, four hundred two million, seven hundred twenty-one thousand, five hundred forty".