1821311641 has 2 divisors, whose sum is σ = 1821311642. Its totient is φ = 1821311640.

The previous prime is 1821311623. The next prime is 1821311647. The reversal of 1821311641 is 1461131281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1795301641 + 26010000 = 42371^2 + 5100^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1821311641 is a prime.

It is a super-2 number, since 2×1821311641² = 6634352187284225762, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1821311647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910655820 + 910655821.

It is an arithmetic number, because the mean of its divisors is an integer number (910655821).

Almost surely, 2^1821311641 is an apocalyptic number.

It is an amenable number.

1821311641 is a deficient number, since it is larger than the sum of its proper divisors (1).

1821311641 is an equidigital number, since it uses as much as digits as its factorization.

1821311641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 28.

The square root of 1821311641 is about 42676.8279163295. The cubic root of 1821311641 is about 1221.2223798164. Note that the first 3 decimals are identical.

The spelling of 1821311641 in words is "one billion, eight hundred twenty-one million, three hundred eleven thousand, six hundred forty-one".