21064631 has 4 divisors (see below), whose sum is σ = 24073872. Its totient is φ = 18055392.

The previous prime is 21064627. The next prime is 21064679. The reversal of 21064631 is 13646012.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21064631 - 2² = 21064627 is a prime.

It is a super-3 number, since 3×21064631³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21064597 and 21064606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21064621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1504610 + ... + 1504623.

It is an arithmetic number, because the mean of its divisors is an integer number (6018468).

Almost surely, 2^21064631 is an apocalyptic number.

21064631 is a deficient number, since it is larger than the sum of its proper divisors (3009241).

21064631 is an equidigital number, since it uses as much as digits as its factorization.

21064631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3009240.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21064631 is about 4589.6220977331. The cubic root of 21064631 is about 276.1751627369.

The spelling of 21064631 in words is "twenty-one million, sixty-four thousand, six hundred thirty-one".