21153238728 has 32 divisors (see below), whose sum is σ = 52899286560. Its totient is φ = 7048920960.

The previous prime is 21153238699. The next prime is 21153238751. The reversal of 21153238728 is 82783235112.

It is a self number, because there is not a number n which added to its sum of digits gives 21153238728.

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, 53893 + ... + 212628.

It is an arithmetic number, because the mean of its divisors is an integer number (1653102705).

Almost surely, 2^21153238728 is an apocalyptic number.

It is an amenable number.

21153238728 is an abundant number, since it is smaller than the sum of its proper divisors (31746047832).

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

21153238728 is a wasteful number, since it uses less digits than its factorization.

21153238728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269837 (or 269833 counting only the distinct ones).

The product of its digits is 161280, while the sum is 42.

The spelling of 21153238728 in words is "twenty-one billion, one hundred fifty-three million, two hundred thirty-eight thousand, seven hundred twenty-eight".