1640666420 has 12 divisors (see below), whose sum is σ = 3445399524. Its totient is φ = 656266560.

The previous prime is 1640666411. The next prime is 1640666437. The reversal of 1640666420 is 246660461.

It can be written as a sum of positive squares in 2 ways, for example, as 529644196 + 1111022224 = 23014^2 + 33332^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41016641 + ... + 41016680.

It is an arithmetic number, because the mean of its divisors is an integer number (287116627).

Almost surely, 2^1640666420 is an apocalyptic number.

1640666420 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1640666420 is an abundant number, since it is smaller than the sum of its proper divisors (1804733104).

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

1640666420 is a wasteful number, since it uses less digits than its factorization.

1640666420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82033330 (or 82033328 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 35.

The square root of 1640666420 is about 40505.1406614025. The cubic root of 1640666420 is about 1179.4334204247.

The spelling of 1640666420 in words is "one billion, six hundred forty million, six hundred sixty-six thousand, four hundred twenty".