21523830 has 32 divisors (see below), whose sum is σ = 52635744. Its totient is φ = 5630976.

The previous prime is 21523813. The next prime is 21523847. The reversal of 21523830 is 3832512.

It is an interprime number because it is at equal distance from previous prime (21523813) and next prime (21523847).

It is a self number, because there is not a number n which added to its sum of digits gives 21523830.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 5179 + ... + 8358.

It is an arithmetic number, because the mean of its divisors is an integer number (1644867).

Almost surely, 2^21523830 is an apocalyptic number.

21523830 is an abundant number, since it is smaller than the sum of its proper divisors (31111914).

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

21523830 is a wasteful number, since it uses less digits than its factorization.

21523830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13600.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 21523830 is about 4639.3781910941. The cubic root of 21523830 is about 278.1675835147.

The spelling of 21523830 in words is "twenty-one million, five hundred twenty-three thousand, eight hundred thirty".