21037397 has 4 divisors (see below), whose sum is σ = 21351456. Its totient is φ = 20723340.

The previous prime is 21037369. The next prime is 21037409. The reversal of 21037397 is 79373012.

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 a de Polignac number, because none of the positive numbers 2^k-21037397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21037897) 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, 156929 + ... + 157062.

It is an arithmetic number, because the mean of its divisors is an integer number (5337864).

Almost surely, 2^21037397 is an apocalyptic number.

It is an amenable number.

21037397 is a deficient number, since it is larger than the sum of its proper divisors (314059).

21037397 is an equidigital number, since it uses as much as digits as its factorization.

21037397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 314058.

The product of its (nonzero) digits is 7938, while the sum is 32.

The square root of 21037397 is about 4586.6542272118. The cubic root of 21037397 is about 276.0560911344.

The spelling of 21037397 in words is "twenty-one million, thirty-seven thousand, three hundred ninety-seven".