21349649 has 4 divisors (see below), whose sum is σ = 21360180. Its totient is φ = 21339120.

The previous prime is 21349621. The next prime is 21349661. The reversal of 21349649 is 94694312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 9412624 + 11937025 = 3068^2 + 3455^2 .

It is a cyclic number.

It is not a de Polignac number, because 21349649 - 2²⁴ = 4572433 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21349849) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1154 + ... + 6635.

It is an arithmetic number, because the mean of its divisors is an integer number (5340045).

Almost surely, 2^21349649 is an apocalyptic number.

It is an amenable number.

21349649 is a deficient number, since it is larger than the sum of its proper divisors (10531).

21349649 is an equidigital number, since it uses as much as digits as its factorization.

21349649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10530.

The product of its digits is 46656, while the sum is 38.

The square root of 21349649 is about 4620.5680386723. The cubic root of 21349649 is about 277.4151957946.

The spelling of 21349649 in words is "twenty-one million, three hundred forty-nine thousand, six hundred forty-nine".