645252130421 has 4 divisors (see below), whose sum is σ = 645279326112. Its totient is φ = 645224934732.

The previous prime is 645252130403. The next prime is 645252130423. The reversal of 645252130421 is 124031252546.

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 645252130421 - 2¹⁸ = 645251868277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645252130423) 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, 13562225 + ... + 13609718.

It is an arithmetic number, because the mean of its divisors is an integer number (161319831528).

Almost surely, 2^645252130421 is an apocalyptic number.

It is an amenable number.

645252130421 is a deficient number, since it is larger than the sum of its proper divisors (27195691).

645252130421 is a wasteful number, since it uses less digits than its factorization.

645252130421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27195690.

The product of its (nonzero) digits is 57600, while the sum is 35.

Adding to 645252130421 its reverse (124031252546), we get a palindrome (769283382967).

The spelling of 645252130421 in words is "six hundred forty-five billion, two hundred fifty-two million, one hundred thirty thousand, four hundred twenty-one".