1645663220553 has 32 divisors (see below), whose sum is σ = 2447992166400. Its totient is φ = 974996568000.

The previous prime is 1645663220533. The next prime is 1645663220587. The reversal of 1645663220553 is 3550223665461.

It is a happy number.

It is not a de Polignac number, because 1645663220553 - 2⁵ = 1645663220521 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1645663220503) 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, 2861683 + ... + 3388296.

It is an arithmetic number, because the mean of its divisors is an integer number (76499755200).

Almost surely, 2^{1645663220553} is an apocalyptic number.

It is an amenable number.

1645663220553 is a deficient number, since it is larger than the sum of its proper divisors (802328945847).

1645663220553 is a wasteful number, since it uses less digits than its factorization.

1645663220553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6250173.

The product of its (nonzero) digits is 3888000, while the sum is 48.

The spelling of 1645663220553 in words is "one trillion, six hundred forty-five billion, six hundred sixty-three million, two hundred twenty thousand, five hundred fifty-three".