21308373 has 16 divisors (see below), whose sum is σ = 32941440. Its totient is φ = 13587552.

The previous prime is 21308369. The next prime is 21308383. The reversal of 21308373 is 37380312.

It is not a de Polignac number, because 21308373 - 2² = 21308369 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21308303) 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, 16536 + ... + 17777.

It is an arithmetic number, because the mean of its divisors is an integer number (2058840).

Almost surely, 2^21308373 is an apocalyptic number.

21308373 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21308373 is a deficient number, since it is larger than the sum of its proper divisors (11633067).

21308373 is a wasteful number, since it uses less digits than its factorization.

21308373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34345 (or 34339 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 27.

The square root of 21308373 is about 4616.0993273542. The cubic root of 21308373 is about 277.2363017243.

Adding to 21308373 its reverse (37380312), we get a palindrome (58688685).

The spelling of 21308373 in words is "twenty-one million, three hundred eight thousand, three hundred seventy-three".