645441701 has 4 divisors (see below), whose sum is σ = 645515532. Its totient is φ = 645367872.

The previous prime is 645441689. The next prime is 645441707. The reversal of 645441701 is 107144546.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 107144546 = 2 ⋅53572273.

It can be written as a sum of positive squares in 2 ways, for example, as 241833601 + 403608100 = 15551^2 + 20090^2 .

It is a cyclic number.

It is not a de Polignac number, because 645441701 - 2¹⁴ = 645425317 is a prime.

It is a super-3 number, since 3×645441701³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645441707) 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, 21716 + ... + 41981.

It is an arithmetic number, because the mean of its divisors is an integer number (161378883).

Almost surely, 2^645441701 is an apocalyptic number.

It is an amenable number.

645441701 is a deficient number, since it is larger than the sum of its proper divisors (73831).

645441701 is a wasteful number, since it uses less digits than its factorization.

645441701 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73830.

The product of its (nonzero) digits is 13440, while the sum is 32.

The square root of 645441701 is about 25405.5446900868. The cubic root of 645441701 is about 864.2094421984.

The spelling of 645441701 in words is "six hundred forty-five million, four hundred forty-one thousand, seven hundred one".