21303780 has 24 divisors (see below), whose sum is σ = 59650752. Its totient is φ = 5680992.

The previous prime is 21303757. The next prime is 21303781. The reversal of 21303780 is 8730312.

It is a self number, because there is not a number n which added to its sum of digits gives 21303780.

It is not an unprimeable number, because it can be changed into a prime (21303781) 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, 177472 + ... + 177591.

It is an arithmetic number, because the mean of its divisors is an integer number (2485448).

Almost surely, 2^21303780 is an apocalyptic number.

21303780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21303780 is an abundant number, since it is smaller than the sum of its proper divisors (38346972).

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

21303780 is a wasteful number, since it uses less digits than its factorization.

21303780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355075 (or 355073 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 24.

The square root of 21303780 is about 4615.6018025822. The cubic root of 21303780 is about 277.2163809505.

The spelling of 21303780 in words is "twenty-one million, three hundred three thousand, seven hundred eighty".