21751313 has 8 divisors (see below), whose sum is σ = 23161320. Its totient is φ = 20355840.

The previous prime is 21751291. The next prime is 21751337. The reversal of 21751313 is 31315712.

It can be written as a sum of positive squares in 4 ways, for example, as 332929 + 21418384 = 577^2 + 4628^2 .

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 21751313 - 2¹² = 21747217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21751343) 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, 458 + ... + 6611.

It is an arithmetic number, because the mean of its divisors is an integer number (2895165).

Almost surely, 2^21751313 is an apocalyptic number.

It is an amenable number.

21751313 is a deficient number, since it is larger than the sum of its proper divisors (1410007).

21751313 is a wasteful number, since it uses less digits than its factorization.

21751313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7267.

The product of its digits is 630, while the sum is 23.

The square root of 21751313 is about 4663.8302927958. The cubic root of 21751313 is about 279.1441254639.

The spelling of 21751313 in words is "twenty-one million, seven hundred fifty-one thousand, three hundred thirteen".