21315436 has 6 divisors (see below), whose sum is σ = 37302020. Its totient is φ = 10657716.

The previous prime is 21315421. The next prime is 21315439. The reversal of 21315436 is 63451312.

It is a self number, because there is not a number n which added to its sum of digits gives 21315436.

It is not an unprimeable number, because it can be changed into a prime (21315439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2664426 + ... + 2664433.

Almost surely, 2^21315436 is an apocalyptic number.

It is an amenable number.

21315436 is a deficient number, since it is larger than the sum of its proper divisors (15986584).

21315436 is a wasteful number, since it uses less digits than its factorization.

21315436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5328863 (or 5328861 counting only the distinct ones).

The product of its digits is 2160, while the sum is 25.

The square root of 21315436 is about 4616.8643038322. The cubic root of 21315436 is about 277.2669298048.

Adding to 21315436 its reverse (63451312), we get a palindrome (84766748).

The spelling of 21315436 in words is "twenty-one million, three hundred fifteen thousand, four hundred thirty-six".