21520838 has 16 divisors (see below), whose sum is σ = 32919936. Its totient is φ = 10549440.

The previous prime is 21520831. The next prime is 21520843. The reversal of 21520838 is 83802512.

It is a self number, because there is not a number n which added to its sum of digits gives 21520838.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520831) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32228 + ... + 32888.

It is an arithmetic number, because the mean of its divisors is an integer number (2057496).

Almost surely, 2^21520838 is an apocalyptic number.

21520838 is a deficient number, since it is larger than the sum of its proper divisors (11399098).

21520838 is a wasteful number, since it uses less digits than its factorization.

21520838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 959.

The product of its (nonzero) digits is 3840, while the sum is 29.

The square root of 21520838 is about 4639.0557228815. The cubic root of 21520838 is about 278.1546936777.

The spelling of 21520838 in words is "twenty-one million, five hundred twenty thousand, eight hundred thirty-eight".