21315670 has 8 divisors (see below), whose sum is σ = 38368224. Its totient is φ = 8526264.

The previous prime is 21315661. The next prime is 21315689. The reversal of 21315670 is 7651312.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1065774 + ... + 1065793.

It is an arithmetic number, because the mean of its divisors is an integer number (4796028).

Almost surely, 2^21315670 is an apocalyptic number.

21315670 is a deficient number, since it is larger than the sum of its proper divisors (17052554).

21315670 is a wasteful number, since it uses less digits than its factorization.

21315670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2131574.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 21315670 is about 4616.8896456381. The cubic root of 21315670 is about 277.2679444094.

Adding to 21315670 its reverse (7651312), we get a palindrome (28966982).

The spelling of 21315670 in words is "twenty-one million, three hundred fifteen thousand, six hundred seventy".