21315064 has 32 divisors (see below), whose sum is σ = 41368320. Its totient is φ = 10290016.

The previous prime is 21315061. The next prime is 21315067. The reversal of 21315064 is 46051312.

It is an interprime number because it is at equal distance from previous prime (21315061) and next prime (21315067).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21315061) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30867 + ... + 31549.

It is an arithmetic number, because the mean of its divisors is an integer number (1292760).

Almost surely, 2^21315064 is an apocalyptic number.

It is an amenable number.

21315064 is a deficient number, since it is larger than the sum of its proper divisors (20053256).

21315064 is a wasteful number, since it uses less digits than its factorization.

21315064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 819 (or 815 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21315064 is about 4616.8240165724. The cubic root of 21315064 is about 277.2653168282.

Adding to 21315064 its reverse (46051312), we get a palindrome (67366376).

The spelling of 21315064 in words is "twenty-one million, three hundred fifteen thousand, sixty-four".