21671697 has 16 divisors (see below), whose sum is σ = 30003200. Its totient is φ = 13899600.

The previous prime is 21671669. The next prime is 21671701. The reversal of 21671697 is 79617612.

It is not a de Polignac number, because 21671697 - 2⁶ = 21671633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21671627) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17922 + ... + 19092.

It is an arithmetic number, because the mean of its divisors is an integer number (1875200).

Almost surely, 2^21671697 is an apocalyptic number.

It is an amenable number.

21671697 is a deficient number, since it is larger than the sum of its proper divisors (8331503).

21671697 is a wasteful number, since it uses less digits than its factorization.

21671697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1404.

The product of its digits is 31752, while the sum is 39.

The square root of 21671697 is about 4655.2869943753. The cubic root of 21671697 is about 278.8031267425.

The spelling of 21671697 in words is "twenty-one million, six hundred seventy-one thousand, six hundred ninety-seven".