21252380 has 24 divisors (see below), whose sum is σ = 47256048. Its totient is φ = 8000768.

The previous prime is 21252377. The next prime is 21252383. The reversal of 21252380 is 8325212.

It is an interprime number because it is at equal distance from previous prime (21252377) and next prime (21252383).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21252383) 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, 30914 + ... + 31593.

It is an arithmetic number, because the mean of its divisors is an integer number (1969002).

Almost surely, 2^21252380 is an apocalyptic number.

21252380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21252380 is an abundant number, since it is smaller than the sum of its proper divisors (26003668).

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

21252380 is a wasteful number, since it uses less digits than its factorization.

21252380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62533 (or 62531 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 21252380 is about 4610.0303686635. The cubic root of 21252380 is about 276.9932531471.

Adding to 21252380 its reverse (8325212), we get a palindrome (29577592).

The spelling of 21252380 in words is "twenty-one million, two hundred fifty-two thousand, three hundred eighty".