661011547541 has 12 divisors (see below), whose sum is σ = 670003014720. Its totient is φ = 652036181160.

The previous prime is 661011547529. The next prime is 661011547543. The reversal of 661011547541 is 145745110166.

It is not a de Polignac number, because 661011547541 - 2¹⁸ = 661011285397 is a prime.

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661011547543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 219530726 + ... + 219533736.

It is an arithmetic number, because the mean of its divisors is an integer number (55833584560).

Almost surely, 2^661011547541 is an apocalyptic number.

It is an amenable number.

661011547541 is a deficient number, since it is larger than the sum of its proper divisors (8991467179).

661011547541 is an frugal number, since it uses more digits than its factorization.

661011547541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6424 (or 4757 counting only the distinct ones).

The product of its (nonzero) digits is 100800, while the sum is 41.

The spelling of 661011547541 in words is "six hundred sixty-one billion, eleven million, five hundred forty-seven thousand, five hundred forty-one".