1215540243 has 64 divisors (see below), whose sum is σ = 1930521600. Its totient is φ = 754686720.

The previous prime is 1215540203. The next prime is 1215540259. The reversal of 1215540243 is 3420455121.

1215540243 is a `hidden beast` number, since 1 + 215 + 5 + 402 + 43 = 666.

It is not a de Polignac number, because 1215540243 - 2²⁵ = 1181985811 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (1215540203) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2416330 + ... + 2416832.

It is an arithmetic number, because the mean of its divisors is an integer number (30164400).

Almost surely, 2^1215540243 is an apocalyptic number.

1215540243 is a deficient number, since it is larger than the sum of its proper divisors (714981357).

1215540243 is a wasteful number, since it uses less digits than its factorization.

1215540243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 649 (or 643 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The square root of 1215540243 is about 34864.5987069979. The cubic root of 1215540243 is about 1067.2261231966.

Adding to 1215540243 its reverse (3420455121), we get a palindrome (4635995364).

The spelling of 1215540243 in words is "one billion, two hundred fifteen million, five hundred forty thousand, two hundred forty-three".