21274561 has 8 divisors (see below), whose sum is σ = 26524224. Its totient is φ = 16577520.

The previous prime is 21274553. The next prime is 21274579. The reversal of 21274561 is 16547212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21274561 - 2³ = 21274553 is a prime.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21274261) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 138070 + ... + 138223.

It is an arithmetic number, because the mean of its divisors is an integer number (3315528).

Almost surely, 2^21274561 is an apocalyptic number.

It is an amenable number.

21274561 is a deficient number, since it is larger than the sum of its proper divisors (5249663).

21274561 is a wasteful number, since it uses less digits than its factorization.

21274561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 276311.

The product of its digits is 3360, while the sum is 28.

The square root of 21274561 is about 4612.4354738034. The cubic root of 21274561 is about 277.0895851203.

The spelling of 21274561 in words is "twenty-one million, two hundred seventy-four thousand, five hundred sixty-one".