21129354810 has 72 divisors (see below), whose sum is σ = 55195467444. Its totient is φ = 5608039680.

The previous prime is 21129354803. The next prime is 21129354853. The reversal of 21129354810 is 1845392112.

21129354810 is a `hidden beast` number, since 2 + 1 + 12 + 93 + 548 + 10 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 21075199929 + 54154881 = 145173^2 + 7359^2 .

It is a super-2 number, since 2×21129354810² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

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 35 ways as a sum of consecutive naturals, for example, 4473250 + ... + 4477970.

Almost surely, 2^21129354810 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21129354810, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27597733722).

21129354810 is an abundant number, since it is smaller than the sum of its proper divisors (34066112634).

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

21129354810 is a wasteful number, since it uses less digits than its factorization.

21129354810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5180 (or 4954 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The spelling of 21129354810 in words is "twenty-one billion, one hundred twenty-nine million, three hundred fifty-four thousand, eight hundred ten".