21575381 has 8 divisors (see below), whose sum is σ = 21840000. Its totient is φ = 21312720.

The previous prime is 21575377. The next prime is 21575387. The reversal of 21575381 is 18357512.

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 21575381 - 2² = 21575377 is a prime.

It is a super-2 number, since 2×21575381² = 930994130590322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21575387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35720 + ... + 36318.

It is an arithmetic number, because the mean of its divisors is an integer number (2730000).

Almost surely, 2^21575381 is an apocalyptic number.

It is an amenable number.

21575381 is a deficient number, since it is larger than the sum of its proper divisors (264619).

21575381 is a wasteful number, since it uses less digits than its factorization.

21575381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 979.

The product of its digits is 8400, while the sum is 32.

The square root of 21575381 is about 4644.9306776313. The cubic root of 21575381 is about 278.3894830563.

The spelling of 21575381 in words is "twenty-one million, five hundred seventy-five thousand, three hundred eighty-one".