21122728540 has 24 divisors (see below), whose sum is σ = 45788625792. Its totient is φ = 8176539840.

The previous prime is 21122728537. The next prime is 21122728553. The reversal of 21122728540 is 4582722112.

It is a junction number, because it is equal to n+sod(n) for n = 21122728496 and 21122728505.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17033839 + ... + 17035078.

It is an arithmetic number, because the mean of its divisors is an integer number (1907859408).

Almost surely, 2^21122728540 is an apocalyptic number.

21122728540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21122728540 is an abundant number, since it is smaller than the sum of its proper divisors (24665897252).

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

21122728540 is a wasteful number, since it uses less digits than its factorization.

21122728540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34068957 (or 34068955 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 34.

The spelling of 21122728540 in words is "twenty-one billion, one hundred twenty-two million, seven hundred twenty-eight thousand, five hundred forty".