661405207462445 has 16 divisors (see below), whose sum is σ = 812155638328320. Its totient is φ = 516811590316224.

The previous prime is 661405207462393. The next prime is 661405207462463. The reversal of 661405207462445 is 544264702504166.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 661405207462445 - 2¹⁰ = 661405207461421 is a prime.

It is a super-2 number, since 2×661405207462445² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 6760589 + ... + 36993458.

It is an arithmetic number, because the mean of its divisors is an integer number (50759727395520).

Almost surely, 2^{661405207462445} is an apocalyptic number.

It is an amenable number.

661405207462445 is a deficient number, since it is larger than the sum of its proper divisors (150750430865875).

661405207462445 is a wasteful number, since it uses less digits than its factorization.

661405207462445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43824404.

The product of its (nonzero) digits is 38707200, while the sum is 56.

The spelling of 661405207462445 in words is "six hundred sixty-one trillion, four hundred five billion, two hundred seven million, four hundred sixty-two thousand, four hundred forty-five".