21007197 has 12 divisors (see below), whose sum is σ = 30584320. Its totient is φ = 13893768.

The previous prime is 21007183. The next prime is 21007199. The reversal of 21007197 is 79170012.

It is not a de Polignac number, because 21007197 - 2⁷ = 21007069 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 21007197.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21007199) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8047 + ... + 10332.

Almost surely, 2^21007197 is an apocalyptic number.

It is an amenable number.

21007197 is a deficient number, since it is larger than the sum of its proper divisors (9577123).

21007197 is a wasteful number, since it uses less digits than its factorization.

21007197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18512 (or 18509 counting only the distinct ones).

The product of its (nonzero) digits is 882, while the sum is 27.

The square root of 21007197 is about 4583.3608847657. The cubic root of 21007197 is about 275.9239314626.

The spelling of 21007197 in words is "twenty-one million, seven thousand, one hundred ninety-seven".