21489649 has 8 divisors (see below), whose sum is σ = 22821480. Its totient is φ = 20165376.

The previous prime is 21489631. The next prime is 21489653. The reversal of 21489649 is 94698412.

It can be written as a sum of positive squares in 4 ways, for example, as 12531600 + 8958049 = 3540^2 + 2993^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21489649 - 2⁹ = 21489137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21489619) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4647 + ... + 8035.

It is an arithmetic number, because the mean of its divisors is an integer number (2852685).

Almost surely, 2^21489649 is an apocalyptic number.

It is an amenable number.

21489649 is a deficient number, since it is larger than the sum of its proper divisors (1331831).

21489649 is a wasteful number, since it uses less digits than its factorization.

21489649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3779.

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

The square root of 21489649 is about 4635.6929363365. The cubic root of 21489649 is about 278.0202571371.

The spelling of 21489649 in words is "twenty-one million, four hundred eighty-nine thousand, six hundred forty-nine".