21297138 has 32 divisors (see below), whose sum is σ = 45219840. Its totient is φ = 6667920.

The previous prime is 21297137. The next prime is 21297139. The reversal of 21297138 is 83179212.

It is an interprime number because it is at equal distance from previous prime (21297137) and next prime (21297139).

It is a junction number, because it is equal to n+sod(n) for n = 21297099 and 21297108.

It is not an unprimeable number, because it can be changed into a prime (21297131) 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, 13743 + ... + 15213.

It is an arithmetic number, because the mean of its divisors is an integer number (1413120).

Almost surely, 2^21297138 is an apocalyptic number.

21297138 is an abundant number, since it is smaller than the sum of its proper divisors (23922702).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21297138 is a wasteful number, since it uses less digits than its factorization.

21297138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1622.

The product of its digits is 6048, while the sum is 33.

The square root of 21297138 is about 4614.8822303500. The cubic root of 21297138 is about 277.1875681829.

The spelling of 21297138 in words is "twenty-one million, two hundred ninety-seven thousand, one hundred thirty-eight".