21012737 has 2 divisors, whose sum is σ = 21012738. Its totient is φ = 21012736.

The previous prime is 21012701. The next prime is 21012743. The reversal of 21012737 is 73721012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19280881 + 1731856 = 4391^2 + 1316^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012737 - 2¹⁰ = 21011713 is a prime.

It is not a weakly prime, because it can be changed into another prime (21012137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506368 + 10506369.

It is an arithmetic number, because the mean of its divisors is an integer number (10506369).

Almost surely, 2^21012737 is an apocalyptic number.

It is an amenable number.

21012737 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012737 is an equidigital number, since it uses as much as digits as its factorization.

21012737 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 588, while the sum is 23.

The square root of 21012737 is about 4583.9652049290. The cubic root of 21012737 is about 275.9481848050.

Adding to 21012737 its reverse (73721012), we get a palindrome (94733749).

The spelling of 21012737 in words is "twenty-one million, twelve thousand, seven hundred thirty-seven".