21151331 has 8 divisors (see below), whose sum is σ = 21896064. Its totient is φ = 20410560.

The previous prime is 21151307. The next prime is 21151343. The reversal of 21151331 is 13315112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21151331 is a prime.

It is a super-2 number, since 2×21151331² = 894757606143122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21150331) 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, 13421 + ... + 14913.

It is an arithmetic number, because the mean of its divisors is an integer number (2737008).

Almost surely, 2^21151331 is an apocalyptic number.

21151331 is a deficient number, since it is larger than the sum of its proper divisors (744733).

21151331 is a wasteful number, since it uses less digits than its factorization.

21151331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1981.

The product of its digits is 90, while the sum is 17.

The square root of 21151331 is about 4599.0576208610. The cubic root of 21151331 is about 276.5535475690.

Adding to 21151331 its reverse (13315112), we get a palindrome (34466443).

The spelling of 21151331 in words is "twenty-one million, one hundred fifty-one thousand, three hundred thirty-one".