661642992 has 200 divisors, whose sum is σ = 2066050800. Its totient is φ = 203655168.

The previous prime is 661642987. The next prime is 661642997. The reversal of 661642992 is 299246166.

661642992 is a `hidden beast` number, since 6 + 616 + 4 + 29 + 9 + 2 = 666.

It is an interprime number because it is at equal distance from previous prime (661642987) and next prime (661642997).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661642997) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 1299634 + ... + 1300142.

It is an arithmetic number, because the mean of its divisors is an integer number (10330254).

Almost surely, 2^661642992 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661642992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1033025400).

661642992 is an abundant number, since it is smaller than the sum of its proper divisors (1404407808).

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

661642992 is a wasteful number, since it uses less digits than its factorization.

661642992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 605 (or 590 counting only the distinct ones).

The product of its digits is 279936, while the sum is 45.

The square root of 661642992 is about 25722.4219699468. The cubic root of 661642992 is about 871.3806378159.

The spelling of 661642992 in words is "six hundred sixty-one million, six hundred forty-two thousand, nine hundred ninety-two".