21351923 has 8 divisors (see below), whose sum is σ = 22302960. Its totient is φ = 20420640.

The previous prime is 21351919. The next prime is 21351943. The reversal of 21351923 is 32915312.

21351923 is an esthetic number in base 13, because in such base its adjacent digits differ by 1.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21351923 - 2² = 21351919 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21351892 and 21351901.

It is not an unprimeable number, because it can be changed into a prime (21351943) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2708 + ... + 7073.

It is an arithmetic number, because the mean of its divisors is an integer number (2787870).

Almost surely, 2^21351923 is an apocalyptic number.

21351923 is a deficient number, since it is larger than the sum of its proper divisors (951037).

21351923 is an equidigital number, since it uses as much as digits as its factorization.

21351923 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9877.

The product of its digits is 1620, while the sum is 26.

The square root of 21351923 is about 4620.8141057610. The cubic root of 21351923 is about 277.4250448208.

The spelling of 21351923 in words is "twenty-one million, three hundred fifty-one thousand, nine hundred twenty-three".