21272745 has 48 divisors (see below), whose sum is σ = 38162880. Its totient is φ = 10055808.

The previous prime is 21272731. The next prime is 21272759. The reversal of 21272745 is 54727212.

It is an interprime number because it is at equal distance from previous prime (21272731) and next prime (21272759).

It is not a de Polignac number, because 21272745 - 2⁶ = 21272681 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 360526 + ... + 360584.

It is an arithmetic number, because the mean of its divisors is an integer number (795060).

Almost surely, 2^21272745 is an apocalyptic number.

It is an amenable number.

21272745 is a deficient number, since it is larger than the sum of its proper divisors (16890135).

21272745 is a wasteful number, since it uses less digits than its factorization.

21272745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166 (or 123 counting only the distinct ones).

The product of its digits is 7840, while the sum is 30.

The square root of 21272745 is about 4612.2386104797. The cubic root of 21272745 is about 277.0817007586.

Adding to 21272745 its reverse (54727212), we get a palindrome (75999957).

The spelling of 21272745 in words is "twenty-one million, two hundred seventy-two thousand, seven hundred forty-five".