2115210821 has 2 divisors, whose sum is σ = 2115210822. Its totient is φ = 2115210820.

The previous prime is 2115210791. The next prime is 2115210833. The reversal of 2115210821 is 1280125112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1456261921 + 658948900 = 38161^2 + 25670^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2115210821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2115210841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1057605410 + 1057605411.

It is an arithmetic number, because the mean of its divisors is an integer number (1057605411).

Almost surely, 2^2115210821 is an apocalyptic number.

It is an amenable number.

2115210821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2115210821 is an equidigital number, since it uses as much as digits as its factorization.

2115210821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 320, while the sum is 23.

The square root of 2115210821 is about 45991.4211674308. The cubic root of 2115210821 is about 1283.6635807342.

Adding to 2115210821 its reverse (1280125112), we get a palindrome (3395335933).

The spelling of 2115210821 in words is "two billion, one hundred fifteen million, two hundred ten thousand, eight hundred twenty-one".