21750037 has 2 divisors, whose sum is σ = 21750038. Its totient is φ = 21750036.

The previous prime is 21750031. The next prime is 21750059. The reversal of 21750037 is 73005712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21288996 + 461041 = 4614^2 + 679^2 .

It is a cyclic number.

It is not a de Polignac number, because 21750037 - 2¹⁹ = 21225749 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21749993 and 21750020.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21750031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10875018 + 10875019.

It is an arithmetic number, because the mean of its divisors is an integer number (10875019).

Almost surely, 2^21750037 is an apocalyptic number.

It is an amenable number.

21750037 is a deficient number, since it is larger than the sum of its proper divisors (1).

21750037 is an equidigital number, since it uses as much as digits as its factorization.

21750037 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1470, while the sum is 25.

The square root of 21750037 is about 4663.6934933591. The cubic root of 21750037 is about 279.1386668683.

Adding to 21750037 its reverse (73005712), we get a palindrome (94755749).

The spelling of 21750037 in words is "twenty-one million, seven hundred fifty thousand, thirty-seven".