21297475 has 6 divisors (see below), whose sum is σ = 26408900. Its totient is φ = 17037960.

The previous prime is 21297469. The next prime is 21297487. The reversal of 21297475 is 57479212.

It is not a de Polignac number, because 21297475 - 2¹⁹ = 20773187 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 425925 + ... + 425974.

Almost surely, 2^21297475 is an apocalyptic number.

21297475 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21297475 is a deficient number, since it is larger than the sum of its proper divisors (5111425).

21297475 is an equidigital number, since it uses as much as digits as its factorization.

21297475 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 851909 (or 851904 counting only the distinct ones).

The product of its digits is 35280, while the sum is 37.

The square root of 21297475 is about 4614.9187425132. The cubic root of 21297475 is about 277.1890302215.

It can be divided in two parts, 2129 and 7475, that added together give a square (9604 = 98²).

The spelling of 21297475 in words is "twenty-one million, two hundred ninety-seven thousand, four hundred seventy-five".