21607697 has 16 divisors (see below), whose sum is σ = 24267600. Its totient is φ = 19138560.

The previous prime is 21607679. The next prime is 21607709. The reversal of 21607697 is 79670612.

It can be written as a sum of positive squares in 8 ways, for example, as 410881 + 21196816 = 641^2 + 4604^2 .

It is a cyclic number.

It is not a de Polignac number, because 21607697 - 2⁶ = 21607633 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 21607697.

It is not an unprimeable number, because it can be changed into a prime (21607657) 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 15 ways as a sum of consecutive naturals, for example, 19679 + ... + 20747.

It is an arithmetic number, because the mean of its divisors is an integer number (1516725).

Almost surely, 2^21607697 is an apocalyptic number.

It is an amenable number.

21607697 is a deficient number, since it is larger than the sum of its proper divisors (2659903).

21607697 is a wasteful number, since it uses less digits than its factorization.

21607697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1156.

The product of its (nonzero) digits is 31752, while the sum is 38.

The square root of 21607697 is about 4648.4080070493. The cubic root of 21607697 is about 278.5284060043.

The spelling of 21607697 in words is "twenty-one million, six hundred seven thousand, six hundred ninety-seven".