661237540 has 48 divisors (see below), whose sum is σ = 1420031088. Its totient is φ = 258545664.

The previous prime is 661237523. The next prime is 661237541. The reversal of 661237540 is 45732166.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 23270976 + 637966564 = 4824^2 + 25258^2 .

It is a junction number, because it is equal to n+sod(n) for n = 661237496 and 661237505.

It is not an unprimeable number, because it can be changed into a prime (661237541) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 330784 + ... + 332776.

It is an arithmetic number, because the mean of its divisors is an integer number (29583981).

Almost surely, 2^661237540 is an apocalyptic number.

It is an amenable number.

661237540 is an abundant number, since it is smaller than the sum of its proper divisors (758793548).

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

661237540 is a wasteful number, since it uses less digits than its factorization.

661237540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2368 (or 2366 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 34.

The square root of 661237540 is about 25714.5394670019. The cubic root of 661237540 is about 871.2026086679.

The spelling of 661237540 in words is "six hundred sixty-one million, two hundred thirty-seven thousand, five hundred forty".