21498649 has 2 divisors, whose sum is σ = 21498650. Its totient is φ = 21498648.

The previous prime is 21498647. The next prime is 21498679. The reversal of 21498649 is 94689412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20866624 + 632025 = 4568^2 + 795^2 .

It is a cyclic number.

It is not a de Polignac number, because 21498649 - 2¹ = 21498647 is a prime.

Together with 21498647, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21498641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10749324 + 10749325.

It is an arithmetic number, because the mean of its divisors is an integer number (10749325).

Almost surely, 2^21498649 is an apocalyptic number.

It is an amenable number.

21498649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21498649 is an equidigital number, since it uses as much as digits as its factorization.

21498649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 124416, while the sum is 43.

The square root of 21498649 is about 4636.6635633826. The cubic root of 21498649 is about 278.0590639302.

The spelling of 21498649 in words is "twenty-one million, four hundred ninety-eight thousand, six hundred forty-nine".