21315739 has 8 divisors (see below), whose sum is σ = 23757840. Its totient is φ = 19005696.

The previous prime is 21315719. The next prime is 21315761. The reversal of 21315739 is 93751312.

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 21315739 - 2⁷ = 21315611 is a prime.

It is a super-2 number, since 2×21315739² = 908721458232242, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21315739.

It is not an unprimeable number, because it can be changed into a prime (21315709) 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, 32674 + ... + 33319.

It is an arithmetic number, because the mean of its divisors is an integer number (2969730).

Almost surely, 2^21315739 is an apocalyptic number.

21315739 is a deficient number, since it is larger than the sum of its proper divisors (2442101).

21315739 is a wasteful number, since it uses less digits than its factorization.

21315739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66029.

The product of its digits is 5670, while the sum is 31.

The square root of 21315739 is about 4616.8971181953. The cubic root of 21315739 is about 277.2682435863.

The spelling of 21315739 in words is "twenty-one million, three hundred fifteen thousand, seven hundred thirty-nine".