21497697 has 32 divisors (see below), whose sum is σ = 34809600. Its totient is φ = 13032576.

The previous prime is 21497689. The next prime is 21497699. The reversal of 21497697 is 79679412.

It is not a de Polignac number, because 21497697 - 2³ = 21497689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21497699) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 25204 + ... + 26042.

It is an arithmetic number, because the mean of its divisors is an integer number (1087800).

Almost surely, 2^21497697 is an apocalyptic number.

21497697 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21497697 is a deficient number, since it is larger than the sum of its proper divisors (13311903).

21497697 is a wasteful number, since it uses less digits than its factorization.

21497697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 934 (or 928 counting only the distinct ones).

The product of its digits is 190512, while the sum is 45.

The square root of 21497697 is about 4636.5609022205. The cubic root of 21497697 is about 278.0549595461.

The spelling of 21497697 in words is "twenty-one million, four hundred ninety-seven thousand, six hundred ninety-seven".