21492497 has 8 divisors (see below), whose sum is σ = 23376360. Its totient is φ = 19641600.

The previous prime is 21492479. The next prime is 21492533. The reversal of 21492497 is 79429412.

It is a Cunningham number, because it is equal to 4636²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 3182656 + 18309841 = 1784^2 + 4279^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21492497 - 2⁶ = 21492433 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 21492497.

It is not an unprimeable number, because it can be changed into a prime (21494497) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6872 + ... + 9497.

It is an arithmetic number, because the mean of its divisors is an integer number (2922045).

Almost surely, 2^21492497 is an apocalyptic number.

It is an amenable number.

21492497 is a deficient number, since it is larger than the sum of its proper divisors (1883863).

21492497 is a wasteful number, since it uses less digits than its factorization.

21492497 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16483.

The product of its digits is 36288, while the sum is 38.

The square root of 21492497 is about 4636.0001078516. Note that the first 3 decimals coincide. The cubic root of 21492497 is about 278.0325385029.

The spelling of 21492497 in words is "twenty-one million, four hundred ninety-two thousand, four hundred ninety-seven".