661581652 has 6 divisors (see below), whose sum is σ = 1157767898. Its totient is φ = 330790824.

The previous prime is 661581649. The next prime is 661581671. The reversal of 661581652 is 256185166.

It can be written as a sum of positive squares in only one way, i.e., 568536336 + 93045316 = 23844^2 + 9646^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82697703 + ... + 82697710.

Almost surely, 2^661581652 is an apocalyptic number.

It is an amenable number.

661581652 is a deficient number, since it is larger than the sum of its proper divisors (496186246).

661581652 is a wasteful number, since it uses less digits than its factorization.

661581652 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165395417 (or 165395415 counting only the distinct ones).

The product of its digits is 86400, while the sum is 40.

The square root of 661581652 is about 25721.2295973579. The cubic root of 661581652 is about 871.3537088221.

The spelling of 661581652 in words is "six hundred sixty-one million, five hundred eighty-one thousand, six hundred fifty-two".