21165313 has 16 divisors (see below), whose sum is σ = 24143616. Its totient is φ = 18406080.

The previous prime is 21165299. The next prime is 21165379. The reversal of 21165313 is 31356112.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21165313 - 2¹³ = 21157121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21165383) 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, 20731 + ... + 21727.

It is an arithmetic number, because the mean of its divisors is an integer number (1508976).

Almost surely, 2^21165313 is an apocalyptic number.

21165313 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21165313 is a deficient number, since it is larger than the sum of its proper divisors (2978303).

21165313 is a wasteful number, since it uses less digits than its factorization.

21165313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1104.

The product of its digits is 540, while the sum is 22.

The square root of 21165313 is about 4600.5774637539. The cubic root of 21165313 is about 276.6144723397.

The spelling of 21165313 in words is "twenty-one million, one hundred sixty-five thousand, three hundred thirteen".