661265001645 has 16 divisors (see below), whose sum is σ = 1058044602240. Its totient is φ = 352667801024.

The previous prime is 661265001583. The next prime is 661265001653. The reversal of 661265001645 is 546100562166.

It is a cyclic number.

It is not a de Polignac number, because 661265001645 - 2⁷ = 661265001517 is a prime.

It is a super-3 number, since 3×661265001645³ (a number of 36 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 661265001597 and 661265001606.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 421312 + ... + 1224758.

It is an arithmetic number, because the mean of its divisors is an integer number (66127787640).

Almost surely, 2^661265001645 is an apocalyptic number.

It is an amenable number.

661265001645 is a deficient number, since it is larger than the sum of its proper divisors (396779600595).

661265001645 is a wasteful number, since it uses less digits than its factorization.

661265001645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 858324.

The product of its (nonzero) digits is 259200, while the sum is 42.

The spelling of 661265001645 in words is "six hundred sixty-one billion, two hundred sixty-five million, one thousand, six hundred forty-five".