215281540 has 96 divisors (see below), whose sum is σ = 499292640. Its totient is φ = 77635584.

The previous prime is 215281481. The next prime is 215281559. The reversal of 215281540 is 45182512.

It can be written as a sum of positive squares in 16 ways, for example, as 1887876 + 213393664 = 1374^2 + 14608^2 .

It is a super-2 number, since 2×215281540² = 92692282929543200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 215281499 and 215281508.

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, 1371142 + ... + 1371298.

It is an arithmetic number, because the mean of its divisors is an integer number (5200965).

Almost surely, 2^215281540 is an apocalyptic number.

215281540 is a gapful number since it is divisible by the number (20) 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 215281540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (249646320).

215281540 is an abundant number, since it is smaller than the sum of its proper divisors (284011100).

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

215281540 is a wasteful number, since it uses less digits than its factorization.

215281540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329 (or 327 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 28.

The square root of 215281540 is about 14672.4755920738. The cubic root of 215281540 is about 599.3340203179.

The spelling of 215281540 in words is "two hundred fifteen million, two hundred eighty-one thousand, five hundred forty".