21949649 has 4 divisors (see below), whose sum is σ = 21960036. Its totient is φ = 21939264.

The previous prime is 21949639. The next prime is 21949663. The reversal of 21949649 is 94694912.

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 8809024 + 13140625 = 2968^2 + 3625^2 .

It is a cyclic number.

It is not a de Polignac number, because 21949649 - 2⁴ = 21949633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21949639) 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, 764 + ... + 6669.

It is an arithmetic number, because the mean of its divisors is an integer number (5490009).

Almost surely, 2^21949649 is an apocalyptic number.

It is an amenable number.

21949649 is a deficient number, since it is larger than the sum of its proper divisors (10387).

21949649 is an equidigital number, since it uses as much as digits as its factorization.

21949649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10386.

The product of its digits is 139968, while the sum is 44.

The square root of 21949649 is about 4685.0452505819. The cubic root of 21949649 is about 279.9900038948.

The spelling of 21949649 in words is "twenty-one million, nine hundred forty-nine thousand, six hundred forty-nine".