21841537 has 2 divisors, whose sum is σ = 21841538. Its totient is φ = 21841536.

The previous prime is 21841489. The next prime is 21841543. The reversal of 21841537 is 73514812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11498881 + 10342656 = 3391^2 + 3216^2 .

It is a cyclic number.

It is not a de Polignac number, because 21841537 - 2⁷ = 21841409 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21841499 and 21841508.

It is not a weakly prime, because it can be changed into another prime (21841037) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10920768 + 10920769.

It is an arithmetic number, because the mean of its divisors is an integer number (10920769).

Almost surely, 2^21841537 is an apocalyptic number.

It is an amenable number.

21841537 is a deficient number, since it is larger than the sum of its proper divisors (1).

21841537 is an equidigital number, since it uses as much as digits as its factorization.

21841537 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6720, while the sum is 31.

The square root of 21841537 is about 4673.4930191453. The cubic root of 21841537 is about 279.5295544052.

It can be divided in two parts, 2184 and 1537, that added together give a square (3721 = 61²).

The spelling of 21841537 in words is "twenty-one million, eight hundred forty-one thousand, five hundred thirty-seven".