21066457 has 2 divisors, whose sum is σ = 21066458. Its totient is φ = 21066456.

The previous prime is 21066449. The next prime is 21066467. The reversal of 21066457 is 75466012.

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., 15515721 + 5550736 = 3939^2 + 2356^2 .

It is a cyclic number.

It is not a de Polignac number, because 21066457 - 2³ = 21066449 is a prime.

It is a super-2 number, since 2×21066457² = 887591221065698, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21066467) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10533228 + 10533229.

It is an arithmetic number, because the mean of its divisors is an integer number (10533229).

Almost surely, 2^21066457 is an apocalyptic number.

It is an amenable number.

21066457 is a deficient number, since it is larger than the sum of its proper divisors (1).

21066457 is an equidigital number, since it uses as much as digits as its factorization.

21066457 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 21066457 is about 4589.8210204756. The cubic root of 21066457 is about 276.1831426421.

The spelling of 21066457 in words is "twenty-one million, sixty-six thousand, four hundred fifty-seven".