21130649 has 2 divisors, whose sum is σ = 21130650. Its totient is φ = 21130648.

The previous prime is 21130619. The next prime is 21130651. The reversal of 21130649 is 94603112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14592400 + 6538249 = 3820^2 + 2557^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21130649 is a prime.

It is a super-2 number, since 2×21130649² = 893008654322402, which contains 22 as substring.

Together with 21130651, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21130619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565324 + 10565325.

It is an arithmetic number, because the mean of its divisors is an integer number (10565325).

Almost surely, 2^21130649 is an apocalyptic number.

It is an amenable number.

21130649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21130649 is an equidigital number, since it uses as much as digits as its factorization.

21130649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 21130649 is about 4596.8085668211. The cubic root of 21130649 is about 276.4633791577.

The spelling of 21130649 in words is "twenty-one million, one hundred thirty thousand, six hundred forty-nine".