21018390144 has 128 divisors (see below), whose sum is σ = 56768532480. Its totient is φ = 6888913920.

The previous prime is 21018390097. The next prime is 21018390179. The reversal of 21018390144 is 44109381012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (128).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13276777 + ... + 13278359.

It is an arithmetic number, because the mean of its divisors is an integer number (443504160).

Almost surely, 2^21018390144 is an apocalyptic number.

21018390144 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 21018390144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28384266240).

21018390144 is an abundant number, since it is smaller than the sum of its proper divisors (35750142336).

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

21018390144 is a wasteful number, since it uses less digits than its factorization.

21018390144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2158 (or 2146 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 33.

The spelling of 21018390144 in words is "twenty-one billion, eighteen million, three hundred ninety thousand, one hundred forty-four".