2181538464 has 288 divisors, whose sum is σ = 7129866240. Its totient is φ = 571748352.

The previous prime is 2181538453. The next prime is 2181538483. The reversal of 2181538464 is 4648351812.

It is a happy number.

It is a super-2 number, since 2×2181538464² = 9518220139822958592, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 9127657 + ... + 9127895.

It is an arithmetic number, because the mean of its divisors is an integer number (24756480).

Almost surely, 2^2181538464 is an apocalyptic number.

2181538464 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 2181538464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3564933120).

2181538464 is an abundant number, since it is smaller than the sum of its proper divisors (4948327776).

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

2181538464 is a wasteful number, since it uses less digits than its factorization.

2181538464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340 (or 315 counting only the distinct ones).

The product of its digits is 184320, while the sum is 42.

The square root of 2181538464 is about 46706.9423533590. The cubic root of 2181538464 is about 1296.9432053229.

The spelling of 2181538464 in words is "two billion, one hundred eighty-one million, five hundred thirty-eight thousand, four hundred sixty-four".