21123310215 has 16 divisors (see below), whose sum is σ = 38625481728. Its totient is φ = 9656370336.

The previous prime is 21123310199. The next prime is 21123310253. The reversal of 21123310215 is 51201332112.

It is not a de Polignac number, because 21123310215 - 2⁴ = 21123310199 is a prime.

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

It is a junction number, because it is equal to n+sod(n) for n = 21123310191 and 21123310200.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 100587087 + ... + 100587296.

It is an arithmetic number, because the mean of its divisors is an integer number (2414092608).

Almost surely, 2^21123310215 is an apocalyptic number.

21123310215 is a deficient number, since it is larger than the sum of its proper divisors (17502171513).

21123310215 is a wasteful number, since it uses less digits than its factorization.

21123310215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201174398.

The product of its (nonzero) digits is 360, while the sum is 21.

Adding to 21123310215 its reverse (51201332112), we get a palindrome (72324642327).

The spelling of 21123310215 in words is "twenty-one billion, one hundred twenty-three million, three hundred ten thousand, two hundred fifteen".