215973540 has 84 divisors (see below), whose sum is σ = 680051484. Its totient is φ = 57589056.

The previous prime is 215973539. The next prime is 215973587. The reversal of 215973540 is 45379512.

215973540 is a `hidden beast` number, since 21 + 5 + 97 + 3 + 540 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 70963776 + 145009764 = 8424^2 + 12042^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 215973495 and 215973504.

It is an unprimeable number.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 7174 + ... + 21986.

It is an arithmetic number, because the mean of its divisors is an integer number (8095851).

Almost surely, 2^215973540 is an apocalyptic number.

215973540 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 215973540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (340025742).

215973540 is an abundant number, since it is smaller than the sum of its proper divisors (464077944).

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

215973540 is a wasteful number, since it uses less digits than its factorization.

215973540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14840 (or 14823 counting only the distinct ones).

The product of its (nonzero) digits is 37800, while the sum is 36.

The square root of 215973540 is about 14696.0382416487. The cubic root of 215973540 is about 599.9754989995.

The spelling of 215973540 in words is "two hundred fifteen million, nine hundred seventy-three thousand, five hundred forty".