8220515661 has 32 divisors (see below), whose sum is σ = 12844540800. Its totient is φ = 5181770880.

The previous prime is 8220515647. The next prime is 8220515687. The reversal of 8220515661 is 1665150228.

8220515661 is a `hidden beast` number, since 82 + 2 + 0 + 515 + 6 + 61 = 666.

It is not a de Polignac number, because 8220515661 - 2¹⁷ = 8220384589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8220511661) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 251895 + ... + 282651.

It is an arithmetic number, because the mean of its divisors is an integer number (401391900).

Almost surely, 2^8220515661 is an apocalyptic number.

It is an amenable number.

8220515661 is a deficient number, since it is larger than the sum of its proper divisors (4624025139).

8220515661 is a wasteful number, since it uses less digits than its factorization.

8220515661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31306 (or 31300 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The square root of 8220515661 is about 90667.0594041739. The cubic root of 8220515661 is about 2018.2099998273.

Adding to 8220515661 its reverse (1665150228), we get a palindrome (9885665889).

The spelling of 8220515661 in words is "eight billion, two hundred twenty million, five hundred fifteen thousand, six hundred sixty-one".