645121103 has 4 divisors (see below), whose sum is σ = 703768488. Its totient is φ = 586473720.

The previous prime is 645121093. The next prime is 645121121. The reversal of 645121103 is 301121546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645121103 - 2²⁴ = 628343887 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 (645121133) 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, 29323676 + ... + 29323697.

It is an arithmetic number, because the mean of its divisors is an integer number (175942122).

Almost surely, 2^645121103 is an apocalyptic number.

645121103 is a deficient number, since it is larger than the sum of its proper divisors (58647385).

645121103 is a wasteful number, since it uses less digits than its factorization.

645121103 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58647384.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 645121103 is about 25399.2342994823. The cubic root of 645121103 is about 864.0663310522.

Adding to 645121103 its reverse (301121546), we get a palindrome (946242649).

The spelling of 645121103 in words is "six hundred forty-five million, one hundred twenty-one thousand, one hundred three".