21405130 has 8 divisors (see below), whose sum is σ = 38529252. Its totient is φ = 8562048.

The previous prime is 21405127. The next prime is 21405149. The reversal of 21405130 is 3150412.

It can be written as a sum of positive squares in 2 ways, for example, as 19368801 + 2036329 = 4401^2 + 1427^2 .

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, 1070247 + ... + 1070266.

Almost surely, 2^21405130 is an apocalyptic number.

21405130 is a deficient number, since it is larger than the sum of its proper divisors (17124122).

21405130 is a wasteful number, since it uses less digits than its factorization.

21405130 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2140520.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21405130 is about 4626.5678423644. The cubic root of 21405130 is about 277.6552927839.

Adding to 21405130 its reverse (3150412), we get a palindrome (24555542).

The spelling of 21405130 in words is "twenty-one million, four hundred five thousand, one hundred thirty".