21266737 has 2 divisors, whose sum is σ = 21266738. Its totient is φ = 21266736.

The previous prime is 21266731. The next prime is 21266753. The reversal of 21266737 is 73766212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19088161 + 2178576 = 4369^2 + 1476^2 .

It is a cyclic number.

It is not a de Polignac number, because 21266737 - 2¹¹ = 21264689 is a prime.

It is not a weakly prime, because it can be changed into another prime (21266731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10633368 + 10633369.

It is an arithmetic number, because the mean of its divisors is an integer number (10633369).

Almost surely, 2^21266737 is an apocalyptic number.

It is an amenable number.

21266737 is a deficient number, since it is larger than the sum of its proper divisors (1).

21266737 is an equidigital number, since it uses as much as digits as its factorization.

21266737 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21168, while the sum is 34.

The square root of 21266737 is about 4611.5872538639. The cubic root of 21266737 is about 277.0556131740.

The spelling of 21266737 in words is "twenty-one million, two hundred sixty-six thousand, seven hundred thirty-seven".