21320355 has 16 divisors (see below), whose sum is σ = 38985984. Its totient is φ = 9746400.

The previous prime is 21320323. The next prime is 21320401. The reversal of 21320355 is 55302312.

21320355 = T₇₉₁ + T₇₉₂ + ... + T₈₅₃.

It is not a de Polignac number, because 21320355 - 2⁵ = 21320323 is a prime.

It is a super-4 number, since 4×21320355⁴ (a number of 30 digits) contains 4444 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 101421 + ... + 101630.

It is an arithmetic number, because the mean of its divisors is an integer number (2436624).

Almost surely, 2^21320355 is an apocalyptic number.

21320355 is a deficient number, since it is larger than the sum of its proper divisors (17665629).

21320355 is a wasteful number, since it uses less digits than its factorization.

21320355 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203066.

The product of its (nonzero) digits is 900, while the sum is 21.

The square root of 21320355 is about 4617.3969939783. The cubic root of 21320355 is about 277.2882566205.

Adding to 21320355 its reverse (55302312), we get a palindrome (76622667).

The spelling of 21320355 in words is "twenty-one million, three hundred twenty thousand, three hundred fifty-five".