1645444997001 has 81 divisors (see below), whose sum is σ = 2661852439701. Its totient is φ = 978994036800.

The previous prime is 1645444996999. The next prime is 1645444997023. The reversal of 1645444997001 is 1007994445461.

It is a happy number.

The square root of 1645444997001 is 1282749.

It is a perfect power (a square), and thus also a powerful number.

1645444997001 is a `hidden beast` number, since 1 + 6 + 4 + 544 + 4 + 9 + 97 + 0 + 0 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 85004318025 + 1560440678976 = 291555^2 + 1249176^2 .

It is not a de Polignac number, because 1645444997001 - 2¹ = 1645444996999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1645444997701) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 1550843011 + ... + 1550844071.

Almost surely, 2^{1645444997001} is an apocalyptic number.

1645444997001 is the 1282749-th square number.

1645444997001 is the 641375-th centered octagonal number.

It is an amenable number.

1645444997001 is a deficient number, since it is larger than the sum of its proper divisors (1016407442700).

1645444997001 is an equidigital number, since it uses as much as digits as its factorization.

1645444997001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2216 (or 1108 counting only the distinct ones).

The product of its (nonzero) digits is 4354560, while the sum is 54.

The spelling of 1645444997001 in words is "one trillion, six hundred forty-five billion, four hundred forty-four million, nine hundred ninety-seven thousand, one".