21069497 has 4 divisors (see below), whose sum is σ = 21191460. Its totient is φ = 20947536.

The previous prime is 21069487. The next prime is 21069547. The reversal of 21069497 is 79496012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8317456 + 12752041 = 2884^2 + 3571^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21069497 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21069497.

It is not an unprimeable number, because it can be changed into a prime (21069487) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60722 + ... + 61067.

It is an arithmetic number, because the mean of its divisors is an integer number (5297865).

Almost surely, 2^21069497 is an apocalyptic number.

It is an amenable number.

21069497 is a deficient number, since it is larger than the sum of its proper divisors (121963).

21069497 is a wasteful number, since it uses less digits than its factorization.

21069497 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121962.

The product of its (nonzero) digits is 27216, while the sum is 38.

The square root of 21069497 is about 4590.1521761266. The cubic root of 21069497 is about 276.1964268941.

The spelling of 21069497 in words is "twenty-one million, sixty-nine thousand, four hundred ninety-seven".