661354554434554 has 4 divisors (see below), whose sum is σ = 992031831651834. Its totient is φ = 330677277217276.

The previous prime is 661354554434551. The next prime is 661354554434599. The reversal of 661354554434554 is 455434455453166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 427566326116329 + 233788228318225 = 20677677^2 + 15290135^2 .

It is not an unprimeable number, because it can be changed into a prime (661354554434551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165338638608637 + ... + 165338638608640.

Almost surely, 2^{661354554434554} is an apocalyptic number.

661354554434554 is a deficient number, since it is larger than the sum of its proper divisors (330677277217280).

661354554434554 is a wasteful number, since it uses less digits than its factorization.

661354554434554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330677277217279.

The product of its digits is 1036800000, while the sum is 64.

The spelling of 661354554434554 in words is "six hundred sixty-one trillion, three hundred fifty-four billion, five hundred fifty-four million, four hundred thirty-four thousand, five hundred fifty-four".