661967964 has 288 divisors, whose sum is σ = 2157442560. Its totient is φ = 173187072.

The previous prime is 661967953. The next prime is 661967983. The reversal of 661967964 is 469769166.

It is a Harshad number since it is a multiple of its sum of digits (54).

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

It is a self number, because there is not a number n which added to its sum of digits gives 661967964.

It is a congruent number.

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, 6824364 + ... + 6824460.

It is an arithmetic number, because the mean of its divisors is an integer number (7491120).

Almost surely, 2^661967964 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 661967964, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1078721280).

661967964 is an abundant number, since it is smaller than the sum of its proper divisors (1495474596).

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

661967964 is a wasteful number, since it uses less digits than its factorization.

661967964 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199 (or 185 counting only the distinct ones).

The product of its digits is 2939328, while the sum is 54.

The square root of 661967964 is about 25728.7380957559. The cubic root of 661967964 is about 871.5232766526.

The spelling of 661967964 in words is "six hundred sixty-one million, nine hundred sixty-seven thousand, nine hundred sixty-four".