661541040 has 320 divisors, whose sum is σ = 2410560000. Its totient is φ = 166505472.

The previous prime is 661541039. The next prime is 661541047. The reversal of 661541040 is 40145166.

661541040 = 373² + 374² + ... + 1267².

661541040 is a `hidden beast` number, since 6 + 615 + 4 + 1 + 0 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 661540995 and 661541013.

It is not an unprimeable number, because it can be changed into a prime (661541047) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3695671 + ... + 3695849.

It is an arithmetic number, because the mean of its divisors is an integer number (7533000).

Almost surely, 2^661541040 is an apocalyptic number.

661541040 is a gapful number since it is divisible by the number (60) 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 661541040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1205280000).

661541040 is an abundant number, since it is smaller than the sum of its proper divisors (1749018960).

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

661541040 is a wasteful number, since it uses less digits than its factorization.

661541040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 289 (or 277 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 661541040 is about 25720.4401206511. The cubic root of 661541040 is about 871.3358787524.

The spelling of 661541040 in words is "six hundred sixty-one million, five hundred forty-one thousand, forty".