21492490 has 8 divisors (see below), whose sum is σ = 38686500. Its totient is φ = 8596992.

The previous prime is 21492479. The next prime is 21492533. The reversal of 21492490 is 9429412.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21003889 + 488601 = 4583^2 + 699^2 .

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1074615 + ... + 1074634.

Almost surely, 2^21492490 is an apocalyptic number.

21492490 is a deficient number, since it is larger than the sum of its proper divisors (17194010).

21492490 is a wasteful number, since it uses less digits than its factorization.

21492490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2149256.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21492490 is about 4635.9993528904. Note that the first 3 decimals coincide. The cubic root of 21492490 is about 278.0325083182.

The spelling of 21492490 in words is "twenty-one million, four hundred ninety-two thousand, four hundred ninety".