21272545 has 16 divisors (see below), whose sum is σ = 29272320. Its totient is φ = 14537664.

The previous prime is 21272527. The next prime is 21272561. The reversal of 21272545 is 54527212.

It is a cyclic number.

It is not a de Polignac number, because 21272545 - 2²¹ = 19175393 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 15 ways as a sum of consecutive naturals, for example, 11719 + ... + 13411.

It is an arithmetic number, because the mean of its divisors is an integer number (1829520).

Almost surely, 2^21272545 is an apocalyptic number.

It is an amenable number.

21272545 is a deficient number, since it is larger than the sum of its proper divisors (7999775).

21272545 is a wasteful number, since it uses less digits than its factorization.

21272545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2064.

The product of its digits is 5600, while the sum is 28.

The square root of 21272545 is about 4612.2169289833. The cubic root of 21272545 is about 277.0808324094.

Adding to 21272545 its reverse (54527212), we get a palindrome (75799757).

The spelling of 21272545 in words is "twenty-one million, two hundred seventy-two thousand, five hundred forty-five".