21390853 has 8 divisors (see below), whose sum is σ = 23776416. Its totient is φ = 19078800.

The previous prime is 21390833. The next prime is 21390857. The reversal of 21390853 is 35809312.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21390853 - 2¹³ = 21382661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21390857) 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, 17763 + ... + 18928.

It is an arithmetic number, because the mean of its divisors is an integer number (2972052).

Almost surely, 2^21390853 is an apocalyptic number.

It is an amenable number.

21390853 is a deficient number, since it is larger than the sum of its proper divisors (2385563).

21390853 is a wasteful number, since it uses less digits than its factorization.

21390853 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36755.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 21390853 is about 4625.0246485830. The cubic root of 21390853 is about 277.5935479860.

The spelling of 21390853 in words is "twenty-one million, three hundred ninety thousand, eight hundred fifty-three".