645061 has 4 divisors (see below), whose sum is σ = 648000. Its totient is φ = 642124.

The previous prime is 645049. The next prime is 645067. The reversal of 645061 is 160546.

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, and also an emirpimes, since its reverse is a distinct semiprime: 160546 = 2 ⋅80273.

It is a cyclic number.

It is not a de Polignac number, because 645061 - 2⁷ = 644933 is a prime.

It is a super-2 number, since 2×645061² = 832207387442, which contains 22 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 (645067) 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, 1111 + ... + 1588.

It is an arithmetic number, because the mean of its divisors is an integer number (162000).

2⁶⁴⁵⁰⁶¹ is an apocalyptic number.

It is an amenable number.

645061 is a deficient number, since it is larger than the sum of its proper divisors (2939).

645061 is a wasteful number, since it uses less digits than its factorization.

645061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2938.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 645061 is about 803.1568962538. The cubic root of 645061 is about 86.4039496508.

The spelling of 645061 in words is "six hundred forty-five thousand, sixty-one".