21001167729 has 32 divisors (see below), whose sum is σ = 31243190400. Its totient is φ = 13942241280.

The previous prime is 21001167701. The next prime is 21001167739. The reversal of 21001167729 is 92776110012.

It is a happy number.

It is not a de Polignac number, because 21001167729 - 2⁵ = 21001167697 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21001167693 and 21001167702.

It is not an unprimeable number, because it can be changed into a prime (21001167739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12970882 + ... + 12972500.

It is an arithmetic number, because the mean of its divisors is an integer number (976349700).

Almost surely, 2^21001167729 is an apocalyptic number.

It is an amenable number.

21001167729 is a deficient number, since it is larger than the sum of its proper divisors (10242022671).

21001167729 is a wasteful number, since it uses less digits than its factorization.

21001167729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3342 (or 3336 counting only the distinct ones).

The product of its (nonzero) digits is 10584, while the sum is 36.

The spelling of 21001167729 in words is "twenty-one billion, one million, one hundred sixty-seven thousand, seven hundred twenty-nine".