656640340 has 24 divisors (see below), whose sum is σ = 1438899840. Its totient is φ = 251236128.

The previous prime is 656640331. The next prime is 656640343. The reversal of 656640340 is 43046656.

It is a super-2 number, since 2×656640340² = 862353072230631200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 656640296 and 656640305.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656640343) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 713280 + ... + 714199.

It is an arithmetic number, because the mean of its divisors is an integer number (59954160).

Almost surely, 2^656640340 is an apocalyptic number.

It is an amenable number.

656640340 is an abundant number, since it is smaller than the sum of its proper divisors (782259500).

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

656640340 is a wasteful number, since it uses less digits than its factorization.

656640340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1427511 (or 1427509 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 34.

The square root of 656640340 is about 25624.9944390238. The cubic root of 656640340 is about 869.1789232296.

Adding to 656640340 its reverse (43046656), we get a palindrome (699686996).

The spelling of 656640340 in words is "six hundred fifty-six million, six hundred forty thousand, three hundred forty".