21313615 has 8 divisors (see below), whose sum is σ = 25603920. Its totient is φ = 17032512.

The previous prime is 21313609. The next prime is 21313657. The reversal of 21313615 is 51631312.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21313615 - 2¹³ = 21305423 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4792 + ... + 8098.

It is an arithmetic number, because the mean of its divisors is an integer number (3200490).

Almost surely, 2^21313615 is an apocalyptic number.

21313615 is a deficient number, since it is larger than the sum of its proper divisors (4290305).

21313615 is a wasteful number, since it uses less digits than its factorization.

21313615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4601.

The product of its digits is 540, while the sum is 22.

The square root of 21313615 is about 4616.6670878459. The cubic root of 21313615 is about 277.2590338453.

Adding to 21313615 its reverse (51631312), we get a palindrome (72944927).

The spelling of 21313615 in words is "twenty-one million, three hundred thirteen thousand, six hundred fifteen".