21351393 has 24 divisors (see below), whose sum is σ = 35425728. Its totient is φ = 12138912.

The previous prime is 21351389. The next prime is 21351401. The reversal of 21351393 is 39315312.

It is a happy number.

It is not a de Polignac number, because 21351393 - 2² = 21351389 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21351353) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13555 + ... + 15047.

It is an arithmetic number, because the mean of its divisors is an integer number (1476072).

Almost surely, 2^21351393 is an apocalyptic number.

It is an amenable number.

21351393 is a deficient number, since it is larger than the sum of its proper divisors (14074335).

21351393 is a wasteful number, since it uses less digits than its factorization.

21351393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1733 (or 1730 counting only the distinct ones).

The product of its digits is 2430, while the sum is 27.

The square root of 21351393 is about 4620.7567562035. The cubic root of 21351393 is about 277.4227493759.

The spelling of 21351393 in words is "twenty-one million, three hundred fifty-one thousand, three hundred ninety-three".