1649420557561 has 4 divisors (see below), whose sum is σ = 1885052065792. Its totient is φ = 1413789049332.

The previous prime is 1649420557553. The next prime is 1649420557573. The reversal of 1649420557561 is 1657550249461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1649420557561 - 2³ = 1649420557553 is a prime.

It is a super-2 number, since 2×1649420557561² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1649420557501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 117815754105 + ... + 117815754118.

It is an arithmetic number, because the mean of its divisors is an integer number (471263016448).

Almost surely, 2^{1649420557561} is an apocalyptic number.

It is an amenable number.

1649420557561 is a deficient number, since it is larger than the sum of its proper divisors (235631508231).

1649420557561 is an equidigital number, since it uses as much as digits as its factorization.

1649420557561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 235631508230.

The product of its (nonzero) digits is 9072000, while the sum is 55.

The spelling of 1649420557561 in words is "one trillion, six hundred forty-nine billion, four hundred twenty million, five hundred fifty-seven thousand, five hundred sixty-one".