1640631556 has 6 divisors (see below), whose sum is σ = 2871105230. Its totient is φ = 820315776.

The previous prime is 1640631457. The next prime is 1640631557. The reversal of 1640631556 is 6551360461.

It can be written as a sum of positive squares in only one way, i.e., 1573391556 + 67240000 = 39666^2 + 8200^2 .

It is a super-2 number, since 2×1640631556² = 5383343805085962272, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1640631557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 205078941 + ... + 205078948.

Almost surely, 2^1640631556 is an apocalyptic number.

It is an amenable number.

1640631556 is a deficient number, since it is larger than the sum of its proper divisors (1230473674).

1640631556 is a wasteful number, since it uses less digits than its factorization.

1640631556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410157893 (or 410157891 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 37.

The square root of 1640631556 is about 40504.7102939893. The cubic root of 1640631556 is about 1179.4250660841.

The spelling of 1640631556 in words is "one billion, six hundred forty million, six hundred thirty-one thousand, five hundred fifty-six".