21009748753988 has 24 divisors (see below), whose sum is σ = 39014275114584. Its totient is φ = 9865493849600.

The previous prime is 21009748753969. The next prime is 21009748754077. The reversal of 21009748753988 is 88935784790012.

It can be written as a sum of positive squares in 4 ways, for example, as 2094364684864 + 18915384069124 = 1447192^2 + 4349182^2 .

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, 335073743 + ... + 335136438.

It is an arithmetic number, because the mean of its divisors is an integer number (1625594796441).

Almost surely, 2^{21009748753988} is an apocalyptic number.

It is an amenable number.

21009748753988 is a deficient number, since it is larger than the sum of its proper divisors (18004526360596).

21009748753988 is a wasteful number, since it uses less digits than its factorization.

21009748753988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 670210663 (or 670210661 counting only the distinct ones).

The product of its (nonzero) digits is 243855360, while the sum is 71.

The spelling of 21009748753988 in words is "twenty-one trillion, nine billion, seven hundred forty-eight million, seven hundred fifty-three thousand, nine hundred eighty-eight".