37640021 has 2 divisors, whose sum is σ = 37640022. Its totient is φ = 37640020.

The previous prime is 37639981. The next prime is 37640033. The reversal of 37640021 is 12004673.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 37039396 + 600625 = 6086^2 + 775^2 .

It is an emirp because it is prime and its reverse (12004673) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 37640021 - 2¹⁸ = 37377877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (37640051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 18820010 + 18820011.

It is an arithmetic number, because the mean of its divisors is an integer number (18820011).

Almost surely, 2^37640021 is an apocalyptic number.

It is an amenable number.

37640021 is a deficient number, since it is larger than the sum of its proper divisors (1).

37640021 is an equidigital number, since it uses as much as digits as its factorization.

37640021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 23.

The square root of 37640021 is about 6135.1463715220. The cubic root of 37640021 is about 335.1325561407.

Adding to 37640021 its reverse (12004673), we get a palindrome (49644694).

The spelling of 37640021 in words is "thirty-seven million, six hundred forty thousand, twenty-one".