661106640 has 40 divisors (see below), whose sum is σ = 2049431328. Its totient is φ = 176295040.

The previous prime is 661106629. The next prime is 661106737. The reversal of 661106640 is 46601166.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 661106598 and 661106607.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1377066 + ... + 1377545.

Almost surely, 2^661106640 is an apocalyptic number.

661106640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661106640 is an abundant number, since it is smaller than the sum of its proper divisors (1388324688).

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

661106640 is a wasteful number, since it uses less digits than its factorization.

661106640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2754627 (or 2754621 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 661106640 is about 25711.9940883627. The cubic root of 661106640 is about 871.1451164957.

The spelling of 661106640 in words is "six hundred sixty-one million, one hundred six thousand, six hundred forty".