21396490 has 32 divisors (see below), whose sum is σ = 40338000. Its totient is φ = 8160768.

The previous prime is 21396481. The next prime is 21396493. The reversal of 21396490 is 9469312.

It can be written as a sum of positive squares in 8 ways, for example, as 6796449 + 14600041 = 2607^2 + 3821^2 .

It is not an unprimeable number, because it can be changed into a prime (21396493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25396 + ... + 26224.

Almost surely, 2^21396490 is an apocalyptic number.

21396490 is a deficient number, since it is larger than the sum of its proper divisors (18941510).

21396490 is a wasteful number, since it uses less digits than its factorization.

21396490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 954.

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 21396490 is about 4625.6340105979. The cubic root of 21396490 is about 277.6179300181.

The spelling of 21396490 in words is "twenty-one million, three hundred ninety-six thousand, four hundred ninety".