16821697 has 4 divisors (see below), whose sum is σ = 16833456. Its totient is φ = 16809940.

The previous prime is 16821691. The next prime is 16821703. The reversal of 16821697 is 79612861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 79612861 = 2377 ⋅33493.

It is an interprime number because it is at equal distance from previous prime (16821691) and next prime (16821703).

It is a cyclic number.

It is not a de Polignac number, because 16821697 - 2³ = 16821689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16821691) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3379 + ... + 6712.

It is an arithmetic number, because the mean of its divisors is an integer number (4208364).

Almost surely, 2^16821697 is an apocalyptic number.

It is an amenable number.

16821697 is a deficient number, since it is larger than the sum of its proper divisors (11759).

16821697 is a wasteful number, since it uses less digits than its factorization.

16821697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11758.

The product of its digits is 36288, while the sum is 40.

The square root of 16821697 is about 4101.4262153548. The cubic root of 16821697 is about 256.2260424162.

Subtracting from 16821697 its product of digits (36288), we obtain a square (16785409 = 4097²).

The spelling of 16821697 in words is "sixteen million, eight hundred twenty-one thousand, six hundred ninety-seven".