21259197 has 24 divisors (see below), whose sum is σ = 33316920. Its totient is φ = 13009920.

The previous prime is 21259193. The next prime is 21259219. The reversal of 21259197 is 79195212.

It can be written as a sum of positive squares in 4 ways, for example, as 6095961 + 15163236 = 2469^2 + 3894^2 .

It is not a de Polignac number, because 21259197 - 2² = 21259193 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21259193) 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 23 ways as a sum of consecutive naturals, for example, 4579 + ... + 7967.

It is an arithmetic number, because the mean of its divisors is an integer number (1388205).

Almost surely, 2^21259197 is an apocalyptic number.

It is an amenable number.

21259197 is a deficient number, since it is larger than the sum of its proper divisors (12057723).

21259197 is a wasteful number, since it uses less digits than its factorization.

21259197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3453 (or 3450 counting only the distinct ones).

The product of its digits is 11340, while the sum is 36.

The square root of 21259197 is about 4610.7696754447. The cubic root of 21259197 is about 277.0228664759.

The spelling of 21259197 in words is "twenty-one million, two hundred fifty-nine thousand, one hundred ninety-seven".