21513250 has 32 divisors (see below), whose sum is σ = 43939584. Its totient is φ = 7822000.

The previous prime is 21513241. The next prime is 21513251. The reversal of 21513250 is 5231512.

It is not an unprimeable number, because it can be changed into a prime (21513251) 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 15 ways as a sum of consecutive naturals, for example, 1162 + ... + 6661.

It is an arithmetic number, because the mean of its divisors is an integer number (1373112).

Almost surely, 2^21513250 is an apocalyptic number.

21513250 is an abundant number, since it is smaller than the sum of its proper divisors (22426334).

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

21513250 is a wasteful number, since it uses less digits than its factorization.

21513250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7851 (or 7841 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 21513250 is about 4638.2378119281. The cubic root of 21513250 is about 278.1219984526.

Adding to 21513250 its reverse (5231512), we get a palindrome (26744762).

The spelling of 21513250 in words is "twenty-one million, five hundred thirteen thousand, two hundred fifty".