661553103506 has 16 divisors (see below), whose sum is σ = 1007459202816. Its totient is φ = 325736493456.

The previous prime is 661553103503. The next prime is 661553103569. The reversal of 661553103506 is 605301355166.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (661553103503) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 355061 + ... + 1203816.

It is an arithmetic number, because the mean of its divisors is an integer number (62966200176).

Almost surely, 2^661553103506 is an apocalyptic number.

661553103506 is a deficient number, since it is larger than the sum of its proper divisors (345906099310).

661553103506 is a wasteful number, since it uses less digits than its factorization.

661553103506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1562113.

The product of its (nonzero) digits is 243000, while the sum is 41.

The spelling of 661553103506 in words is "six hundred sixty-one billion, five hundred fifty-three million, one hundred three thousand, five hundred six".