661142988 has 216 divisors, whose sum is σ = 1991349360. Its totient is φ = 183306240.

The previous prime is 661142987. The next prime is 661143001. The reversal of 661142988 is 889241166.

661142988 is a `hidden beast` number, since 6 + 611 + 4 + 29 + 8 + 8 = 666.

It is a super-2 number, since 2×661142988² = 874220101163136288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (661142987) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 6065478 + ... + 6065586.

It is an arithmetic number, because the mean of its divisors is an integer number (9219210).

Almost surely, 2^661142988 is an apocalyptic number.

661142988 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661142988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (995674680).

661142988 is an abundant number, since it is smaller than the sum of its proper divisors (1330206372).

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

661142988 is a wasteful number, since it uses less digits than its factorization.

661142988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217 (or 195 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The square root of 661142988 is about 25712.7009083060. The cubic root of 661142988 is about 871.1610815461.

The spelling of 661142988 in words is "six hundred sixty-one million, one hundred forty-two thousand, nine hundred eighty-eight".