20121989904 has 45 divisors (see below), whose sum is σ = 56318388789. Its totient is φ = 6706762560.

The previous prime is 20121989813. The next prime is 20121989977. The reversal of 20121989904 is 40998912102.

The square root of 20121989904 is 141852.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 2761292304 + 17360697600 = 52548^2 + 131760^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 20121989904.

It is an unprimeable number.

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 8 ways as a sum of consecutive naturals, for example, 1696314 + ... + 1708134.

Almost surely, 2^20121989904 is an apocalyptic number.

20121989904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

20121989904 is the 141852-nd square number.

It is an amenable number.

20121989904 is an abundant number, since it is smaller than the sum of its proper divisors (36196398885).

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

20121989904 is an frugal number, since it uses more digits than its factorization.

20121989904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23656 (or 11826 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 45.

It can be divided in two parts, 20121 and 989904, that added together give a square (1010025 = 1005²).

The spelling of 20121989904 in words is "twenty billion, one hundred twenty-one million, nine hundred eighty-nine thousand, nine hundred four".