661667741405541 has 24 divisors (see below), whose sum is σ = 1030552350205560. Its totient is φ = 406669257472896.

The previous prime is 661667741405527. The next prime is 661667741405581. The reversal of 661667741405541 is 145504147766166.

661667741405541 is a `hidden beast` number, since 6 + 6 + 1 + 6 + 6 + 7 + 7 + 41 + 40 + 5 + 541 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 198002750625 + 661469738654916 = 444975^2 + 25719054^2 .

It is not a de Polignac number, because 661667741405541 - 2⁹ = 661667741405029 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661667741405581) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3547761106 + ... + 3547947603.

It is an arithmetic number, because the mean of its divisors is an integer number (42939681258565).

Almost surely, 2^{661667741405541} is an apocalyptic number.

It is an amenable number.

661667741405541 is a deficient number, since it is larger than the sum of its proper divisors (368884608800019).

661667741405541 is a wasteful number, since it uses less digits than its factorization.

661667741405541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7095709525 (or 7095709522 counting only the distinct ones).

The product of its (nonzero) digits is 101606400, while the sum is 63.

The spelling of 661667741405541 in words is "six hundred sixty-one trillion, six hundred sixty-seven billion, seven hundred forty-one million, four hundred five thousand, five hundred forty-one".