2100021990 has 64 divisors (see below), whose sum is σ = 5588428032. Its totient is φ = 500745600.

The previous prime is 2100021961. The next prime is 2100021991. The reversal of 2100021990 is 991200012.

It is a self number, because there is not a number n which added to its sum of digits gives 2100021990.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2100021991) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 32032 + ... + 72291.

It is an arithmetic number, because the mean of its divisors is an integer number (87319188).

Almost surely, 2^2100021990 is an apocalyptic number.

2100021990 is an abundant number, since it is smaller than the sum of its proper divisors (3488406042).

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

2100021990 is a wasteful number, since it uses less digits than its factorization.

2100021990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104405.

The product of its (nonzero) digits is 324, while the sum is 24.

The square root of 2100021990 is about 45825.9968795006. The cubic root of 2100021990 is about 1280.5836348030.

The spelling of 2100021990 in words is "two billion, one hundred million, twenty-one thousand, nine hundred ninety".