645621493 has 4 divisors (see below), whose sum is σ = 704314368. Its totient is φ = 586928620.

The previous prime is 645621491. The next prime is 645621521. The reversal of 645621493 is 394126546.

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 645621493 - 2¹ = 645621491 is a prime.

It is a super-2 number, since 2×645621493² = 833654224447098098, 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 (645621491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29346421 + ... + 29346442.

It is an arithmetic number, because the mean of its divisors is an integer number (176078592).

Almost surely, 2^645621493 is an apocalyptic number.

It is an amenable number.

645621493 is a deficient number, since it is larger than the sum of its proper divisors (58692875).

645621493 is a wasteful number, since it uses less digits than its factorization.

645621493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58692874.

The product of its digits is 155520, while the sum is 40.

The square root of 645621493 is about 25409.0828838823. The cubic root of 645621493 is about 864.2896784763.

The spelling of 645621493 in words is "six hundred forty-five million, six hundred twenty-one thousand, four hundred ninety-three".