21347437 has 4 divisors (see below), whose sum is σ = 22036096. Its totient is φ = 20658780.

The previous prime is 21347423. The next prime is 21347441. The reversal of 21347437 is 73474312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21347437 - 2⁷ = 21347309 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 688627 = 21347437 / (2 + 1 + 3 + 4 + 7 + 4 + 3 + 7).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21347399 and 21347408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21347467) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 344283 + ... + 344344.

It is an arithmetic number, because the mean of its divisors is an integer number (5509024).

Almost surely, 2^21347437 is an apocalyptic number.

It is an amenable number.

21347437 is a deficient number, since it is larger than the sum of its proper divisors (688659).

21347437 is an equidigital number, since it uses as much as digits as its factorization.

21347437 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 688658.

The product of its digits is 14112, while the sum is 31.

The square root of 21347437 is about 4620.3286679629. The cubic root of 21347437 is about 277.4056146284.

The spelling of 21347437 in words is "twenty-one million, three hundred forty-seven thousand, four hundred thirty-seven".