21297771 has 24 divisors (see below), whose sum is σ = 34347456. Its totient is φ = 12605040.

The previous prime is 21297767. The next prime is 21297779. The reversal of 21297771 is 17779212.

It is not a de Polignac number, because 21297771 - 2² = 21297767 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21297779) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1756 + ... + 6758.

It is an arithmetic number, because the mean of its divisors is an integer number (1431144).

Almost surely, 2^21297771 is an apocalyptic number.

21297771 is a deficient number, since it is larger than the sum of its proper divisors (13049685).

21297771 is a wasteful number, since it uses less digits than its factorization.

21297771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5063 (or 5060 counting only the distinct ones).

The product of its digits is 12348, while the sum is 36.

The square root of 21297771 is about 4614.9508123056. The cubic root of 21297771 is about 277.1903143733.

It can be divided in two parts, 21 and 297771, that added together give a palindrome (297792).

The spelling of 21297771 in words is "twenty-one million, two hundred ninety-seven thousand, seven hundred seventy-one".