1640838337921 has 2 divisors, whose sum is σ = 1640838337922. Its totient is φ = 1640838337920.

The previous prime is 1640838337913. The next prime is 1640838337939. The reversal of 1640838337921 is 1297338380461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1048246297921 + 592592040000 = 1023839^2 + 769800^2 .

It is a cyclic number.

It is not a de Polignac number, because 1640838337921 - 2³ = 1640838337913 is a prime.

It is not a weakly prime, because it can be changed into another prime (1640838337981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820419168960 + 820419168961.

It is an arithmetic number, because the mean of its divisors is an integer number (820419168961).

Almost surely, 2^{1640838337921} is an apocalyptic number.

It is an amenable number.

1640838337921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1640838337921 is an equidigital number, since it uses as much as digits as its factorization.

1640838337921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5225472, while the sum is 55.

The spelling of 1640838337921 in words is "one trillion, six hundred forty billion, eight hundred thirty-eight million, three hundred thirty-seven thousand, nine hundred twenty-one".