21207953 has 8 divisors (see below), whose sum is σ = 23043048. Its totient is φ = 19401984.

The previous prime is 21207881. The next prime is 21207997. The reversal of 21207953 is 35970212.

It can be written as a sum of positive squares in 4 ways, for example, as 350464 + 20857489 = 592^2 + 4567^2 .

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 21207953 - 2¹² = 21203857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21207853) 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, 5750 + ... + 8687.

It is an arithmetic number, because the mean of its divisors is an integer number (2880381).

Almost surely, 2^21207953 is an apocalyptic number.

It is an amenable number.

21207953 is a deficient number, since it is larger than the sum of its proper divisors (1835095).

21207953 is a wasteful number, since it uses less digits than its factorization.

21207953 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14563.

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 21207953 is about 4605.2093329185. The cubic root of 21207953 is about 276.8001051446.

The spelling of 21207953 in words is "twenty-one million, two hundred seven thousand, nine hundred fifty-three".