21430037 has 2 divisors, whose sum is σ = 21430038. Its totient is φ = 21430036.

The previous prime is 21430033. The next prime is 21430063. The reversal of 21430037 is 73003412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19280881 + 2149156 = 4391^2 + 1466^2 .

It is a cyclic number.

It is not a de Polignac number, because 21430037 - 2² = 21430033 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21430033) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10715018 + 10715019.

It is an arithmetic number, because the mean of its divisors is an integer number (10715019).

Almost surely, 2^21430037 is an apocalyptic number.

It is an amenable number.

21430037 is a deficient number, since it is larger than the sum of its proper divisors (1).

21430037 is an equidigital number, since it uses as much as digits as its factorization.

21430037 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 504, while the sum is 20.

The square root of 21430037 is about 4629.2587959629. The cubic root of 21430037 is about 277.7629442331.

Adding to 21430037 its reverse (73003412), we get a palindrome (94433449).

The spelling of 21430037 in words is "twenty-one million, four hundred thirty thousand, thirty-seven".