644121477123 has 8 divisors (see below), whose sum is σ = 866855072448. Its totient is φ = 425401099944.

The previous prime is 644121477047. The next prime is 644121477133. The reversal of 644121477123 is 321774121446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 644121477123 - 2⁹ = 644121476611 is a prime.

It is a super-2 number, since 2×644121477123² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (644121477133) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1003304161 + ... + 1003304802.

It is an arithmetic number, because the mean of its divisors is an integer number (108356884056).

Almost surely, 2^644121477123 is an apocalyptic number.

644121477123 is a deficient number, since it is larger than the sum of its proper divisors (222733595325).

644121477123 is a wasteful number, since it uses less digits than its factorization.

644121477123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2006609073.

The product of its digits is 225792, while the sum is 42.

Adding to 644121477123 its reverse (321774121446), we get a palindrome (965895598569).

The spelling of 644121477123 in words is "six hundred forty-four billion, one hundred twenty-one million, four hundred seventy-seven thousand, one hundred twenty-three".