215688390 has 32 divisors (see below), whose sum is σ = 534352896. Its totient is φ = 55661280.

The previous prime is 215688371. The next prime is 215688419. The reversal of 215688390 is 93886512.

215688390 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 115032 + ... + 116891.

It is an arithmetic number, because the mean of its divisors is an integer number (16698528).

Almost surely, 2^215688390 is an apocalyptic number.

215688390 is an abundant number, since it is smaller than the sum of its proper divisors (318664506).

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

215688390 is a wasteful number, since it uses less digits than its factorization.

215688390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 231964.

The product of its (nonzero) digits is 103680, while the sum is 42.

The square root of 215688390 is about 14686.3334430347. Note that the first 3 decimals coincide. The cubic root of 215688390 is about 599.7113333638.

The spelling of 215688390 in words is "two hundred fifteen million, six hundred eighty-eight thousand, three hundred ninety".