661220620 has 12 divisors (see below), whose sum is σ = 1388563344. Its totient is φ = 264488240.

The previous prime is 661220603. The next prime is 661220621. The reversal of 661220620 is 26022166.

661220620 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (661220621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16530496 + ... + 16530535.

It is an arithmetic number, because the mean of its divisors is an integer number (115713612).

Almost surely, 2^661220620 is an apocalyptic number.

It is an amenable number.

661220620 is an abundant number, since it is smaller than the sum of its proper divisors (727342724).

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

661220620 is a wasteful number, since it uses less digits than its factorization.

661220620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33061040 (or 33061038 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 661220620 is about 25714.2104681439. The cubic root of 661220620 is about 871.1951777156.

Adding to 661220620 its reverse (26022166), we get a palindrome (687242786).

The spelling of 661220620 in words is "six hundred sixty-one million, two hundred twenty thousand, six hundred twenty".