21487697 has 16 divisors (see below), whose sum is σ = 26956800. Its totient is φ = 16639440.

The previous prime is 21487693. The next prime is 21487699. The reversal of 21487697 is 79678412.

It is a cyclic number.

It is not a de Polignac number, because 21487697 - 2² = 21487693 is a prime.

It is a super-2 number, since 2×21487697² = 923442244727618, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21487693) 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, 13004 + ... + 14562.

It is an arithmetic number, because the mean of its divisors is an integer number (1684800).

Almost surely, 2^21487697 is an apocalyptic number.

It is an amenable number.

21487697 is a deficient number, since it is larger than the sum of its proper divisors (5469103).

21487697 is a wasteful number, since it uses less digits than its factorization.

21487697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1756.

The product of its digits is 169344, while the sum is 44.

The square root of 21487697 is about 4635.4823912944. The cubic root of 21487697 is about 278.0118389451.

The spelling of 21487697 in words is "twenty-one million, four hundred eighty-seven thousand, six hundred ninety-seven".