661518044544 has 96 divisors (see below), whose sum is σ = 2044040189400. Its totient is φ = 189005150208.

The previous prime is 661518044519. The next prime is 661518044569. The reversal of 661518044544 is 445440815166.

It is an interprime number because it is at equal distance from previous prime (661518044519) and next prime (661518044569).

It is a tau number, because it is divible by the number of its divisors (96).

It is a super-2 number, since 2×661518044544² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a junction number, because it is equal to n+sod(n) for n = 661518044493 and 661518044502.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17559789 + ... + 17597420.

Almost surely, 2^661518044544 is an apocalyptic number.

661518044544 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

661518044544 is an abundant number, since it is smaller than the sum of its proper divisors (1382522144856).

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

661518044544 is a wasteful number, since it uses less digits than its factorization.

661518044544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35157240 (or 35157221 counting only the distinct ones).

The product of its (nonzero) digits is 1843200, while the sum is 48.

The spelling of 661518044544 in words is "six hundred sixty-one billion, five hundred eighteen million, forty-four thousand, five hundred forty-four".