21745037 has 4 divisors (see below), whose sum is σ = 21790176. Its totient is φ = 21699900.

The previous prime is 21745033. The next prime is 21745039. The reversal of 21745037 is 73054712.

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 21745037 - 2² = 21745033 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 (21745033) 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, 21839 + ... + 22812.

It is an arithmetic number, because the mean of its divisors is an integer number (5447544).

Almost surely, 2^21745037 is an apocalyptic number.

It is an amenable number.

21745037 is a deficient number, since it is larger than the sum of its proper divisors (45139).

21745037 is an equidigital number, since it uses as much as digits as its factorization.

21745037 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45138.

The product of its (nonzero) digits is 5880, while the sum is 29.

The square root of 21745037 is about 4663.1574067363. The cubic root of 21745037 is about 279.1172753292.

Adding to 21745037 its reverse (73054712), we get a palindrome (94799749).

It can be divided in two parts, 217 and 45037, that added together give a palindrome (45254).

The spelling of 21745037 in words is "twenty-one million, seven hundred forty-five thousand, thirty-seven".