21728475 has 36 divisors (see below), whose sum is σ = 39171600. Its totient is φ = 11513280.

The previous prime is 21728471. The next prime is 21728513. The reversal of 21728475 is 57482712.

It is not a de Polignac number, because 21728475 - 2² = 21728471 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21728471) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 60346 + ... + 60704.

It is an arithmetic number, because the mean of its divisors is an integer number (1088100).

Almost surely, 2^21728475 is an apocalyptic number.

21728475 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21728475 is a deficient number, since it is larger than the sum of its proper divisors (17443125).

21728475 is a wasteful number, since it uses less digits than its factorization.

21728475 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644 (or 636 counting only the distinct ones).

The product of its digits is 31360, while the sum is 36.

The square root of 21728475 is about 4661.3812330682. The cubic root of 21728475 is about 279.0463945663.

The spelling of 21728475 in words is "twenty-one million, seven hundred twenty-eight thousand, four hundred seventy-five".