644545401553650 has 192 divisors, whose sum is σ = 1689789112289280. Its totient is φ = 162323508614400.

The previous prime is 644545401553607. The next prime is 644545401553673. The reversal of 644545401553650 is 56355104545446.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 339872565 + ... + 341763735.

It is an arithmetic number, because the mean of its divisors is an integer number (8800984959840).

Almost surely, 2^{644545401553650} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644545401553650, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (844894556144640).

644545401553650 is an abundant number, since it is smaller than the sum of its proper divisors (1045243710735630).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644545401553650 is a wasteful number, since it uses less digits than its factorization.

644545401553650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1892929 (or 1892924 counting only the distinct ones).

The product of its (nonzero) digits is 86400000, while the sum is 57.

The spelling of 644545401553650 in words is "six hundred forty-four trillion, five hundred forty-five billion, four hundred one million, five hundred fifty-three thousand, six hundred fifty".