21158441984 has 44 divisors (see below), whose sum is σ = 42327112704. Its totient is φ = 10571495424.

The previous prime is 21158441981. The next prime is 21158441987. The reversal of 21158441984 is 48914485112.

It is an interprime number because it is at equal distance from previous prime (21158441981) and next prime (21158441987).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21158441981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1552769 + ... + 1566335.

Almost surely, 2^21158441984 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 21158441984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21163556352).

21158441984 is an abundant number, since it is smaller than the sum of its proper divisors (21168670720).

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

21158441984 is a wasteful number, since it uses less digits than its factorization.

21158441984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15110 (or 15092 counting only the distinct ones).

The product of its digits is 368640, while the sum is 47.

The spelling of 21158441984 in words is "twenty-one billion, one hundred fifty-eight million, four hundred forty-one thousand, nine hundred eighty-four".