21315597 has 8 divisors (see below), whose sum is σ = 28565856. Its totient is φ = 14137872.

The previous prime is 21315583. The next prime is 21315599. The reversal of 21315597 is 79551312.

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

It is not a de Polignac number, because 21315597 - 2⁸ = 21315341 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21315599) 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, 17443 + ... + 18624.

It is an arithmetic number, because the mean of its divisors is an integer number (3570732).

Almost surely, 2^21315597 is an apocalyptic number.

It is an amenable number.

21315597 is a deficient number, since it is larger than the sum of its proper divisors (7250259).

21315597 is a wasteful number, since it uses less digits than its factorization.

21315597 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36267.

The product of its digits is 9450, while the sum is 33.

The square root of 21315597 is about 4616.8817398760. The cubic root of 21315597 is about 277.2676278883.

It can be divided in two parts, 21315 and 597, that added together give a palindrome (21912).

The spelling of 21315597 in words is "twenty-one million, three hundred fifteen thousand, five hundred ninety-seven".