21003042120 has 128 divisors (see below), whose sum is σ = 66047667840. Its totient is φ = 5337077760.

The previous prime is 21003042059. The next prime is 21003042121. The reversal of 21003042120 is 2124030012.

It is a super-2 number, since 2×21003042120² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21003042120.

It is not an unprimeable number, because it can be changed into a prime (21003042121) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 161922 + ... + 261198.

It is an arithmetic number, because the mean of its divisors is an integer number (515997405).

Almost surely, 2^21003042120 is an apocalyptic number.

21003042120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21003042120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33023833920).

21003042120 is an abundant number, since it is smaller than the sum of its proper divisors (45044625720).

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

21003042120 is a wasteful number, since it uses less digits than its factorization.

21003042120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99375 (or 99371 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

Adding to 21003042120 its reverse (2124030012), we get a palindrome (23127072132).

The spelling of 21003042120 in words is "twenty-one billion, three million, forty-two thousand, one hundred twenty".