2189779956 has 144 divisors (see below), whose sum is σ = 6829373824. Its totient is φ = 576108288.

The previous prime is 2189779939. The next prime is 2189779957. The reversal of 2189779956 is 6599779812.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a junction number, because it is equal to n+sod(n) for n = 2189779893 and 2189779902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2189779957) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2479491 + ... + 2480373.

Almost surely, 2^2189779956 is an apocalyptic number.

2189779956 is a gapful number since it is divisible by the number (26) 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 2189779956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3414686912).

2189779956 is an abundant number, since it is smaller than the sum of its proper divisors (4639593868).

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

2189779956 is a wasteful number, since it uses less digits than its factorization.

2189779956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1670 (or 1665 counting only the distinct ones).

The product of its digits is 17146080, while the sum is 63.

The square root of 2189779956 is about 46795.0847418829. The cubic root of 2189779956 is about 1298.5743653658.

The spelling of 2189779956 in words is "two billion, one hundred eighty-nine million, seven hundred seventy-nine thousand, nine hundred fifty-six".