21071497 has 2 divisors, whose sum is σ = 21071498. Its totient is φ = 21071496.

The previous prime is 21071489. The next prime is 21071503. The reversal of 21071497 is 79417012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17214201 + 3857296 = 4149^2 + 1964^2 .

It is a cyclic number.

It is not a de Polignac number, because 21071497 - 2³ = 21071489 is a prime.

It is not a weakly prime, because it can be changed into another prime (21071447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10535748 + 10535749.

It is an arithmetic number, because the mean of its divisors is an integer number (10535749).

Almost surely, 2^21071497 is an apocalyptic number.

It is an amenable number.

21071497 is a deficient number, since it is larger than the sum of its proper divisors (1).

21071497 is an equidigital number, since it uses as much as digits as its factorization.

21071497 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3528, while the sum is 31.

The square root of 21071497 is about 4590.3700286578. The cubic root of 21071497 is about 276.2051658368.

The spelling of 21071497 in words is "twenty-one million, seventy-one thousand, four hundred ninety-seven".