21475837 has 2 divisors, whose sum is σ = 21475838. Its totient is φ = 21475836.

The previous prime is 21475819. The next prime is 21475889. The reversal of 21475837 is 73857412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19131876 + 2343961 = 4374^2 + 1531^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21475837 is a prime.

It is a super-2 number, since 2×21475837² = 922423149701138, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21475796 and 21475805.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21475807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10737918 + 10737919.

It is an arithmetic number, because the mean of its divisors is an integer number (10737919).

Almost surely, 2^21475837 is an apocalyptic number.

It is an amenable number.

21475837 is a deficient number, since it is larger than the sum of its proper divisors (1).

21475837 is an equidigital number, since it uses as much as digits as its factorization.

21475837 is an evil number, because the sum of its binary digits is even.

The product of its digits is 47040, while the sum is 37.

The square root of 21475837 is about 4634.2029519649. The cubic root of 21475837 is about 277.9606805664.

The spelling of 21475837 in words is "twenty-one million, four hundred seventy-five thousand, eight hundred thirty-seven".