20987100 has 90 divisors (see below), whose sum is σ = 68058144. Its totient is φ = 5594400.

The previous prime is 20987089. The next prime is 20987119. The reversal of 20987100 is 178902.

It is a tau number, because it is divible by the number of its divisors (90).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 6805 + ... + 9395.

Almost surely, 2^20987100 is an apocalyptic number.

20987100 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 20987100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34029072).

20987100 is an abundant number, since it is smaller than the sum of its proper divisors (47071044).

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

20987100 is a wasteful number, since it uses less digits than its factorization.

20987100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2617 (or 2601 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 20987100 is about 4581.1679733448. The cubic root of 20987100 is about 275.8359138098.

The spelling of 20987100 in words is "twenty million, nine hundred eighty-seven thousand, one hundred".