21136649 has 2 divisors, whose sum is σ = 21136650. Its totient is φ = 21136648.

The previous prime is 21136613. The next prime is 21136663. The reversal of 21136649 is 94663112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14961424 + 6175225 = 3868^2 + 2485^2 .

It is a cyclic number.

It is not a de Polignac number, because 21136649 - 2⁸ = 21136393 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21136669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10568324 + 10568325.

It is an arithmetic number, because the mean of its divisors is an integer number (10568325).

Almost surely, 2^21136649 is an apocalyptic number.

It is an amenable number.

21136649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21136649 is an equidigital number, since it uses as much as digits as its factorization.

21136649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776, while the sum is 32.

The square root of 21136649 is about 4597.4611471985. The cubic root of 21136649 is about 276.4895437318.

The spelling of 21136649 in words is "twenty-one million, one hundred thirty-six thousand, six hundred forty-nine".