21255131 has 8 divisors (see below), whose sum is σ = 21974640. Its totient is φ = 20543328.

The previous prime is 21255127. The next prime is 21255133. The reversal of 21255131 is 13155212.

It is a happy number.

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 21255131 - 2² = 21255127 is a prime.

It is a super-2 number, since 2×21255131² = 903561187654322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21255133) 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, 3980 + ... + 7638.

It is an arithmetic number, because the mean of its divisors is an integer number (2746830).

Almost surely, 2^21255131 is an apocalyptic number.

21255131 is a deficient number, since it is larger than the sum of its proper divisors (719509).

21255131 is a wasteful number, since it uses less digits than its factorization.

21255131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3853.

The product of its digits is 300, while the sum is 20.

The square root of 21255131 is about 4610.3287301450. The cubic root of 21255131 is about 277.0052043664.

The spelling of 21255131 in words is "twenty-one million, two hundred fifty-five thousand, one hundred thirty-one".