21697907 has 8 divisors (see below), whose sum is σ = 27052032. Its totient is φ = 16907400.

The previous prime is 21697889. The next prime is 21697909. The reversal of 21697907 is 70979612.

It is a happy number.

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 21697907 - 2¹² = 21693811 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21697909) 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, 140819 + ... + 140972.

It is an arithmetic number, because the mean of its divisors is an integer number (3381504).

Almost surely, 2^21697907 is an apocalyptic number.

21697907 is a deficient number, since it is larger than the sum of its proper divisors (5354125).

21697907 is a wasteful number, since it uses less digits than its factorization.

21697907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 281809.

The product of its (nonzero) digits is 47628, while the sum is 41.

The square root of 21697907 is about 4658.1012226013. The cubic root of 21697907 is about 278.9154773663.

The spelling of 21697907 in words is "twenty-one million, six hundred ninety-seven thousand, nine hundred seven".