21328770 has 16 divisors (see below), whose sum is σ = 51189120. Its totient is φ = 5687664.

The previous prime is 21328763. The next prime is 21328781. The reversal of 21328770 is 7782312.

It is a Harshad number since it is a multiple of its sum of digits (30), and also a Moran number because the ratio is a prime number: 710959 = 21328770 / (2 + 1 + 3 + 2 + 8 + 7 + 7 + 0).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 355450 + ... + 355509.

It is an arithmetic number, because the mean of its divisors is an integer number (3199320).

Almost surely, 2^21328770 is an apocalyptic number.

21328770 is an abundant number, since it is smaller than the sum of its proper divisors (29860350).

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

21328770 is a wasteful number, since it uses less digits than its factorization.

21328770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 710969.

The product of its (nonzero) digits is 4704, while the sum is 30.

The square root of 21328770 is about 4618.3081317729. The cubic root of 21328770 is about 277.3247330887.

The spelling of 21328770 in words is "twenty-one million, three hundred twenty-eight thousand, seven hundred seventy".