21501099984 has 160 divisors (see below), whose sum is σ = 68455618560. Its totient is φ = 5662895616.

The previous prime is 21501099923. The next prime is 21501100039. The reversal of 21501099984 is 48999010512.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3661819 + ... + 3667685.

It is an arithmetic number, because the mean of its divisors is an integer number (427847616).

Almost surely, 2^21501099984 is an apocalyptic number.

21501099984 is a gapful number since it is divisible by the number (24) 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 21501099984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34227809280).

21501099984 is an abundant number, since it is smaller than the sum of its proper divisors (46954518576).

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

21501099984 is a wasteful number, since it uses less digits than its factorization.

21501099984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6737 (or 6731 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 48.

The spelling of 21501099984 in words is "twenty-one billion, five hundred one million, ninety-nine thousand, nine hundred eighty-four".