2130721 has 2 divisors, whose sum is σ = 2130722. Its totient is φ = 2130720.

The previous prime is 2130703. The next prime is 2130727. The reversal of 2130721 is 1270312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2073600 + 57121 = 1440^2 + 239^2 .

It is a cyclic number.

It is not a de Polignac number, because 2130721 - 2⁹ = 2130209 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2130695 and 2130704.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2130727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1065360 + 1065361.

It is an arithmetic number, because the mean of its divisors is an integer number (1065361).

2^2130721 is an apocalyptic number.

It is an amenable number.

2130721 is a deficient number, since it is larger than the sum of its proper divisors (1).

2130721 is an equidigital number, since it uses as much as digits as its factorization.

2130721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 2130721 is about 1459.6989415630. The cubic root of 2130721 is about 128.6793510662.

The spelling of 2130721 in words is "two million, one hundred thirty thousand, seven hundred twenty-one".