21395390 has 8 divisors (see below), whose sum is σ = 38511720. Its totient is φ = 8558152.

The previous prime is 21395383. The next prime is 21395393. The reversal of 21395390 is 9359312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a plaindrome in base 16.

It is a zygodrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21395393) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1069760 + ... + 1069779.

It is an arithmetic number, because the mean of its divisors is an integer number (4813965).

Almost surely, 2^21395390 is an apocalyptic number.

21395390 is a deficient number, since it is larger than the sum of its proper divisors (17116330).

21395390 is a wasteful number, since it uses less digits than its factorization.

21395390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2139546.

The product of its (nonzero) digits is 7290, while the sum is 32.

The square root of 21395390 is about 4625.5151064503. The cubic root of 21395390 is about 277.6131724628.

The spelling of 21395390 in words is "twenty-one million, three hundred ninety-five thousand, three hundred ninety".