644401261545155 has 8 divisors (see below), whose sum is σ = 773288134945872. Its totient is φ = 515516595175008.

The previous prime is 644401261545133. The next prime is 644401261545157. The reversal of 644401261545155 is 551545162104446.

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

It is a cyclic number.

It is not a de Polignac number, because 644401261545155 - 2¹⁴ = 644401261528771 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644401261545097 and 644401261545106.

It is not an unprimeable number, because it can be changed into a prime (644401261545157) 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, 551115224 + ... + 552283253.

It is an arithmetic number, because the mean of its divisors is an integer number (96661016868234).

Almost surely, 2^{644401261545155} is an apocalyptic number.

644401261545155 is a deficient number, since it is larger than the sum of its proper divisors (128886873400717).

644401261545155 is a wasteful number, since it uses less digits than its factorization.

644401261545155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1103515285.

The product of its (nonzero) digits is 11520000, while the sum is 53.

The spelling of 644401261545155 in words is "six hundred forty-four trillion, four hundred one billion, two hundred sixty-one million, five hundred forty-five thousand, one hundred fifty-five".