21683437 has 2 divisors, whose sum is σ = 21683438. Its totient is φ = 21683436.

The previous prime is 21683429. The next prime is 21683491. The reversal of 21683437 is 73438612.

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., 20529961 + 1153476 = 4531^2 + 1074^2 .

It is a cyclic number.

It is not a de Polignac number, because 21683437 - 2³ = 21683429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21683537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10841718 + 10841719.

It is an arithmetic number, because the mean of its divisors is an integer number (10841719).

Almost surely, 2^21683437 is an apocalyptic number.

It is an amenable number.

21683437 is a deficient number, since it is larger than the sum of its proper divisors (1).

21683437 is an equidigital number, since it uses as much as digits as its factorization.

21683437 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192, while the sum is 34.

The square root of 21683437 is about 4656.5477555803. The cubic root of 21683437 is about 278.8534620999.

The spelling of 21683437 in words is "twenty-one million, six hundred eighty-three thousand, four hundred thirty-seven".