7215640666 has 16 divisors (see below), whose sum is σ = 11673280584. Its totient is φ = 3325368384.

The previous prime is 7215640657. The next prime is 7215640673. The reversal of 7215640666 is 6660465127.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 4952640625 + 2263000041 = 70375^2 + 47571^2 .

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 187365 + ... + 222568.

Almost surely, 2^7215640666 is an apocalyptic number.

7215640666 is a deficient number, since it is larger than the sum of its proper divisors (4457639918).

7215640666 is a wasteful number, since it uses less digits than its factorization.

7215640666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410625.

The product of its (nonzero) digits is 362880, while the sum is 43.

The square root of 7215640666 is about 84944.9272528972. The cubic root of 7215640666 is about 1932.3759891682.

The spelling of 7215640666 in words is "seven billion, two hundred fifteen million, six hundred forty thousand, six hundred sixty-six".