215978397 has 4 divisors (see below), whose sum is σ = 287971200. Its totient is φ = 143985596.

The previous prime is 215978383. The next prime is 215978401. The reversal of 215978397 is 793879512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 215978397 - 2⁴ = 215978381 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215978317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35996397 + ... + 35996402.

It is an arithmetic number, because the mean of its divisors is an integer number (71992800).

Almost surely, 2^215978397 is an apocalyptic number.

It is an amenable number.

215978397 is a deficient number, since it is larger than the sum of its proper divisors (71992803).

215978397 is an equidigital number, since it uses as much as digits as its factorization.

215978397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71992802.

The product of its digits is 952560, while the sum is 51.

The square root of 215978397 is about 14696.2034893370. The cubic root of 215978397 is about 599.9799965553.

The spelling of 215978397 in words is "two hundred fifteen million, nine hundred seventy-eight thousand, three hundred ninety-seven".