21759490 has 16 divisors (see below), whose sum is σ = 41471352. Its totient is φ = 8191744.

The previous prime is 21759487. The next prime is 21759497. The reversal of 21759490 is 9495712.

It can be written as a sum of positive squares in 4 ways, for example, as 21058921 + 700569 = 4589^2 + 837^2 .

It is not an unprimeable number, because it can be changed into a prime (21759497) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 63829 + ... + 64168.

Almost surely, 2^21759490 is an apocalyptic number.

21759490 is a deficient number, since it is larger than the sum of its proper divisors (19711862).

21759490 is a wasteful number, since it uses less digits than its factorization.

21759490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128021.

The product of its (nonzero) digits is 22680, while the sum is 37.

The square root of 21759490 is about 4664.7068503819. The cubic root of 21759490 is about 279.1791007556.

The spelling of 21759490 in words is "twenty-one million, seven hundred fifty-nine thousand, four hundred ninety".