21385730 has 32 divisors (see below), whose sum is σ = 39804480. Its totient is φ = 8268480.

The previous prime is 21385717. The next prime is 21385733. The reversal of 21385730 is 3758312.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21385693 and 21385702.

It is not an unprimeable number, because it can be changed into a prime (21385733) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39260 + ... + 39800.

It is an arithmetic number, because the mean of its divisors is an integer number (1243890).

Almost surely, 2^21385730 is an apocalyptic number.

21385730 is a deficient number, since it is larger than the sum of its proper divisors (18418750).

21385730 is a wasteful number, since it uses less digits than its factorization.

21385730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 674.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 21385730 is about 4624.4707805326. The cubic root of 21385730 is about 277.5713854711.

The spelling of 21385730 in words is "twenty-one million, three hundred eighty-five thousand, seven hundred thirty".