21007331 has 4 divisors (see below), whose sum is σ = 22113000. Its totient is φ = 19901664.

The previous prime is 21007321. The next prime is 21007423. The reversal of 21007331 is 13370012.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21007331 - 2¹⁴ = 20990947 is a prime.

It is a super-2 number, since 2×21007331² = 882615911487122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21007321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 552806 + ... + 552843.

It is an arithmetic number, because the mean of its divisors is an integer number (5528250).

Almost surely, 2^21007331 is an apocalyptic number.

21007331 is a deficient number, since it is larger than the sum of its proper divisors (1105669).

21007331 is a wasteful number, since it uses less digits than its factorization.

21007331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1105668.

The product of its (nonzero) digits is 126, while the sum is 17.

The square root of 21007331 is about 4583.3755028363. The cubic root of 21007331 is about 275.9245181461.

Adding to 21007331 its reverse (13370012), we get a palindrome (34377343).

The spelling of 21007331 in words is "twenty-one million, seven thousand, three hundred thirty-one".