21101320 has 16 divisors (see below), whose sum is σ = 47478060. Its totient is φ = 8440512.

The previous prime is 21101317. The next prime is 21101323. The reversal of 21101320 is 2310112.

It is an interprime number because it is at equal distance from previous prime (21101317) and next prime (21101323).

It can be written as a sum of positive squares in 2 ways, for example, as 20738916 + 362404 = 4554^2 + 602^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 21101297 and 21101306.

It is not an unprimeable number, because it can be changed into a prime (21101323) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 263727 + ... + 263806.

Almost surely, 2^21101320 is an apocalyptic number.

21101320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21101320 is an abundant number, since it is smaller than the sum of its proper divisors (26376740).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21101320 is a wasteful number, since it uses less digits than its factorization.

21101320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 527544 (or 527540 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21101320 is about 4593.6173110088. The cubic root of 21101320 is about 276.3354110297.

Adding to 21101320 its reverse (2310112), we get a palindrome (23411432).

The spelling of 21101320 in words is "twenty-one million, one hundred one thousand, three hundred twenty".