21046530 has 64 divisors (see below), whose sum is σ = 52690176. Its totient is φ = 5376000.

The previous prime is 21046513. The next prime is 21046537. The reversal of 21046530 is 3564012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21046497 and 21046506.

It is not an unprimeable number, because it can be changed into a prime (21046537) 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 31 ways as a sum of consecutive naturals, for example, 87210 + ... + 87450.

It is an arithmetic number, because the mean of its divisors is an integer number (823284).

Almost surely, 2^21046530 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21046530, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26345088).

21046530 is an abundant number, since it is smaller than the sum of its proper divisors (31643646).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21046530 is a wasteful number, since it uses less digits than its factorization.

21046530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 363.

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 21046530 is about 4587.6497250771. The cubic root of 21046530 is about 276.0960335842.

The spelling of 21046530 in words is "twenty-one million, forty-six thousand, five hundred thirty".