215422978 has 4 divisors (see below), whose sum is σ = 323134470. Its totient is φ = 107711488.

The previous prime is 215422973. The next prime is 215423027. The reversal of 215422978 is 879224512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 215414329 + 8649 = 14677^2 + 93^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 215422978.

It is not an unprimeable number, because it can be changed into a prime (215422973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 53855743 + ... + 53855746.

Almost surely, 2^215422978 is an apocalyptic number.

215422978 is a deficient number, since it is larger than the sum of its proper divisors (107711492).

215422978 is a wasteful number, since it uses less digits than its factorization.

215422978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107711491.

The product of its digits is 80640, while the sum is 40.

The square root of 215422978 is about 14677.2946417247. The cubic root of 215422978 is about 599.4652439052.

The spelling of 215422978 in words is "two hundred fifteen million, four hundred twenty-two thousand, nine hundred seventy-eight".