20979800 has 48 divisors (see below), whose sum is σ = 51354600. Its totient is φ = 7948800.

The previous prime is 20979799. The next prime is 20979809. The reversal of 20979800 is 897902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20979809) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1040 + ... + 6560.

Almost surely, 2^20979800 is an apocalyptic number.

20979800 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 20979800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25677300).

20979800 is an abundant number, since it is smaller than the sum of its proper divisors (30374800).

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

20979800 is a wasteful number, since it uses less digits than its factorization.

20979800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5556 (or 5547 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 35.

The square root of 20979800 is about 4580.3711639997. The cubic root of 20979800 is about 275.8039285159.

It can be divided in two parts, 209 and 79800, that multiplied together give a triangular number (16678200 = T₅₇₇₅).

The spelling of 20979800 in words is "twenty million, nine hundred seventy-nine thousand, eight hundred".