1001921681 has 2 divisors, whose sum is σ = 1001921682. Its totient is φ = 1001921680.

The previous prime is 1001921671. The next prime is 1001921729. The reversal of 1001921681 is 1861291001.

1001921681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 796142656 + 205779025 = 28216^2 + 14345^2 .

It is a cyclic number.

It is not a de Polignac number, because 1001921681 - 2⁶ = 1001921617 is a prime.

It is a super-2 number, since 2×1001921681² = 2007694109715731522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1001921651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 500960840 + 500960841.

It is an arithmetic number, because the mean of its divisors is an integer number (500960841).

Almost surely, 2^1001921681 is an apocalyptic number.

It is an amenable number.

1001921681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1001921681 is an equidigital number, since it uses as much as digits as its factorization.

1001921681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 29.

The square root of 1001921681 is about 31653.1464628716. The cubic root of 1001921681 is about 1000.6401504533.

The spelling of 1001921681 in words is "one billion, one million, nine hundred twenty-one thousand, six hundred eighty-one".