21953405 has 8 divisors (see below), whose sum is σ = 26374200. Its totient is φ = 17542656.

The previous prime is 21953387. The next prime is 21953411. The reversal of 21953405 is 50435912.

It can be written as a sum of positive squares in 4 ways, for example, as 811801 + 21141604 = 901^2 + 4598^2 .

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 21953405 - 2⁸ = 21953149 is a prime.

It is a congruent 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, 3701 + ... + 7589.

It is an arithmetic number, because the mean of its divisors is an integer number (3296775).

Almost surely, 2^21953405 is an apocalyptic number.

It is an amenable number.

21953405 is a deficient number, since it is larger than the sum of its proper divisors (4420795).

21953405 is a wasteful number, since it uses less digits than its factorization.

21953405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5023.

The product of its (nonzero) digits is 5400, while the sum is 29.

The square root of 21953405 is about 4685.4460833521. The cubic root of 21953405 is about 280.0059735120.

The spelling of 21953405 in words is "twenty-one million, nine hundred fifty-three thousand, four hundred five".