1221700666501 has 32 divisors (see below), whose sum is σ = 1504118359040. Its totient is φ = 968842353024.

The previous prime is 1221700666409. The next prime is 1221700666523. The reversal of 1221700666501 is 1056660071221.

It is a happy number.

It is not a de Polignac number, because 1221700666501 - 2²⁵ = 1221667112069 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221700666561) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 55137241 + ... + 55159393.

It is an arithmetic number, because the mean of its divisors is an integer number (47003698720).

Almost surely, 2^{1221700666501} is an apocalyptic number.

It is an amenable number.

1221700666501 is a deficient number, since it is larger than the sum of its proper divisors (282417692539).

1221700666501 is a wasteful number, since it uses less digits than its factorization.

1221700666501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31865.

The product of its (nonzero) digits is 30240, while the sum is 37.

The spelling of 1221700666501 in words is "one trillion, two hundred twenty-one billion, seven hundred million, six hundred sixty-six thousand, five hundred one".