645001621 has 4 divisors (see below), whose sum is σ = 703638144. Its totient is φ = 586365100.

The previous prime is 645001603. The next prime is 645001661. The reversal of 645001621 is 126100546.

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 645001621 - 2¹¹ = 644999573 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645001661) 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, 29318245 + ... + 29318266.

It is an arithmetic number, because the mean of its divisors is an integer number (175909536).

Almost surely, 2^645001621 is an apocalyptic number.

It is an amenable number.

645001621 is a deficient number, since it is larger than the sum of its proper divisors (58636523).

645001621 is a wasteful number, since it uses less digits than its factorization.

645001621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58636522.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 645001621 is about 25396.8821117869. The cubic root of 645001621 is about 864.0129835762.

The spelling of 645001621 in words is "six hundred forty-five million, one thousand, six hundred twenty-one".