20998431616 has 64 divisors (see below), whose sum is σ = 42454011600. Its totient is φ = 10344017920.

The previous prime is 20998431613. The next prime is 20998431659. The reversal of 20998431616 is 61613489902.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (64).

It is a self number, because there is not a number n which added to its sum of digits gives 20998431616.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20998431613) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4130196 + ... + 4135276.

Almost surely, 2^20998431616 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20998431616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21227005800).

20998431616 is an abundant number, since it is smaller than the sum of its proper divisors (21455579984).

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

20998431616 is an equidigital number, since it uses as much as digits as its factorization.

20998431616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5567 (or 5555 counting only the distinct ones).

The product of its (nonzero) digits is 559872, while the sum is 49.

The spelling of 20998431616 in words is "twenty billion, nine hundred ninety-eight million, four hundred thirty-one thousand, six hundred sixteen".