261666515232101 has 32 divisors (see below), whose sum is σ = 300655103508480. Its totient is φ = 223081695383616.

The previous prime is 261666515232097. The next prime is 261666515232131. The reversal of 261666515232101 is 101232515666162.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 261666515232101 - 2² = 261666515232097 is a prime.

It is a super-2 number, since 2×261666515232101² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261666515232131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 14570207360 + ... + 14570225318.

It is an arithmetic number, because the mean of its divisors is an integer number (9395471984640).

Almost surely, 2^{261666515232101} is an apocalyptic number.

It is an amenable number.

261666515232101 is a deficient number, since it is larger than the sum of its proper divisors (38988588276379).

261666515232101 is a wasteful number, since it uses less digits than its factorization.

261666515232101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25953.

The product of its (nonzero) digits is 777600, while the sum is 47.

The spelling of 261666515232101 in words is "two hundred sixty-one trillion, six hundred sixty-six billion, five hundred fifteen million, two hundred thirty-two thousand, one hundred one".