645510121421 has 32 divisors (see below), whose sum is σ = 763605501696. Its totient is φ = 539136640000.

The previous prime is 645510121393. The next prime is 645510121453. The reversal of 645510121421 is 124121015546.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-645510121421 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645510120421) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1100291 + ... + 1581663.

It is an arithmetic number, because the mean of its divisors is an integer number (23862671928).

Almost surely, 2^645510121421 is an apocalyptic number.

It is an amenable number.

645510121421 is a deficient number, since it is larger than the sum of its proper divisors (118095380275).

645510121421 is a wasteful number, since it uses less digits than its factorization.

645510121421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 481573.

The product of its (nonzero) digits is 9600, while the sum is 32.

Adding to 645510121421 its reverse (124121015546), we get a palindrome (769631136967).

The spelling of 645510121421 in words is "six hundred forty-five billion, five hundred ten million, one hundred twenty-one thousand, four hundred twenty-one".