21680697 has 8 divisors (see below), whose sum is σ = 30164544. Its totient is φ = 13825328.

The previous prime is 21680689. The next prime is 21680699. The reversal of 21680697 is 79608612.

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 21680697 - 2³ = 21680689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21680699) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 157038 + ... + 157175.

It is an arithmetic number, because the mean of its divisors is an integer number (3770568).

Almost surely, 2^21680697 is an apocalyptic number.

It is an amenable number.

21680697 is a deficient number, since it is larger than the sum of its proper divisors (8483847).

21680697 is a wasteful number, since it uses less digits than its factorization.

21680697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 314239.

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 21680697 is about 4656.2535369114. The cubic root of 21680697 is about 278.8417159505.

The spelling of 21680697 in words is "twenty-one million, six hundred eighty thousand, six hundred ninety-seven".