2691871921 has 2 divisors, whose sum is σ = 2691871922. Its totient is φ = 2691871920.

The previous prime is 2691871891. The next prime is 2691871943. The reversal of 2691871921 is 1291781962.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1856661921 + 835210000 = 43089^2 + 28900^2 .

It is a cyclic number.

It is not a de Polignac number, because 2691871921 - 2¹³ = 2691863729 is a prime.

It is not a weakly prime, because it can be changed into another prime (2691871951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1345935960 + 1345935961.

It is an arithmetic number, because the mean of its divisors is an integer number (1345935961).

Almost surely, 2^2691871921 is an apocalyptic number.

It is an amenable number.

2691871921 is a deficient number, since it is larger than the sum of its proper divisors (1).

2691871921 is an equidigital number, since it uses as much as digits as its factorization.

2691871921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 46.

The square root of 2691871921 is about 51883.2527989524. The cubic root of 2691871921 is about 1391.0779418560.

The spelling of 2691871921 in words is "two billion, six hundred ninety-one million, eight hundred seventy-one thousand, nine hundred twenty-one".