1645564554121 has 4 divisors (see below), whose sum is σ = 1668741519744. Its totient is φ = 1622387588500.

The previous prime is 1645564554119. The next prime is 1645564554131. The reversal of 1645564554121 is 1214554655461.

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 1645564554121 - 2¹ = 1645564554119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1645564554131) 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, 11588482705 + ... + 11588482846.

It is an arithmetic number, because the mean of its divisors is an integer number (417185379936).

Almost surely, 2^{1645564554121} is an apocalyptic number.

It is an amenable number.

1645564554121 is a deficient number, since it is larger than the sum of its proper divisors (23176965623).

1645564554121 is an equidigital number, since it uses as much as digits as its factorization.

1645564554121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23176965622.

The product of its digits is 2880000, while the sum is 49.

The spelling of 1645564554121 in words is "one trillion, six hundred forty-five billion, five hundred sixty-four million, five hundred fifty-four thousand, one hundred twenty-one".