21951305 has 8 divisors (see below), whose sum is σ = 26418312. Its totient is φ = 17509888.

The previous prime is 21951263. The next prime is 21951329. The reversal of 21951305 is 50315912.

It can be written as a sum of positive squares in 4 ways, for example, as 11449 + 21939856 = 107^2 + 4684^2 .

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 21951305 - 2²⁰ = 20902729 is a prime.

It is a Duffinian 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, 4454 + ... + 7983.

It is an arithmetic number, because the mean of its divisors is an integer number (3302289).

Almost surely, 2^21951305 is an apocalyptic number.

It is an amenable number.

21951305 is a deficient number, since it is larger than the sum of its proper divisors (4467007).

21951305 is a wasteful number, since it uses less digits than its factorization.

21951305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12795.

The product of its (nonzero) digits is 1350, while the sum is 26.

The square root of 21951305 is about 4685.2219797999. The cubic root of 21951305 is about 279.9970450368.

The spelling of 21951305 in words is "twenty-one million, nine hundred fifty-one thousand, three hundred five".