21387297 has 16 divisors (see below), whose sum is σ = 30191040. Its totient is φ = 13444032.

The previous prime is 21387287. The next prime is 21387299. The reversal of 21387297 is 79278312.

It is not a de Polignac number, because 21387297 - 2¹⁴ = 21370913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21387299) 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, 883 + ... + 6599.

It is an arithmetic number, because the mean of its divisors is an integer number (1886940).

Almost surely, 2^21387297 is an apocalyptic number.

It is an amenable number.

21387297 is a deficient number, since it is larger than the sum of its proper divisors (8803743).

21387297 is a wasteful number, since it uses less digits than its factorization.

21387297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5792.

The product of its digits is 42336, while the sum is 39.

The square root of 21387297 is about 4624.6402022211. The cubic root of 21387297 is about 277.5781648163.

The spelling of 21387297 in words is "twenty-one million, three hundred eighty-seven thousand, two hundred ninety-seven".