1640766401 has 2 divisors, whose sum is σ = 1640766402. Its totient is φ = 1640766400.

The previous prime is 1640766377. The next prime is 1640766473. The reversal of 1640766401 is 1046670461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 891321025 + 749445376 = 29855^2 + 27376^2 .

It is a cyclic number.

It is not a de Polignac number, because 1640766401 - 2²² = 1636572097 is a prime.

It is a super-2 number, since 2×1640766401² = 5384228765300985602, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1640768401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820383200 + 820383201.

It is an arithmetic number, because the mean of its divisors is an integer number (820383201).

Almost surely, 2^1640766401 is an apocalyptic number.

It is an amenable number.

1640766401 is a deficient number, since it is larger than the sum of its proper divisors (1).

1640766401 is an equidigital number, since it uses as much as digits as its factorization.

1640766401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 35.

The square root of 1640766401 is about 40506.3748192800. The cubic root of 1640766401 is about 1179.4573778719.

The spelling of 1640766401 in words is "one billion, six hundred forty million, seven hundred sixty-six thousand, four hundred one".