21206293 has 4 divisors (see below), whose sum is σ = 22453740. Its totient is φ = 19958848.

The previous prime is 21206249. The next prime is 21206303. The reversal of 21206293 is 39260212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15856324 + 5349969 = 3982^2 + 2313^2 .

It is a cyclic number.

It is not a de Polignac number, because 21206293 - 2⁹ = 21205781 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21206233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 623698 + ... + 623731.

It is an arithmetic number, because the mean of its divisors is an integer number (5613435).

Almost surely, 2^21206293 is an apocalyptic number.

It is an amenable number.

21206293 is a deficient number, since it is larger than the sum of its proper divisors (1247447).

21206293 is a wasteful number, since it uses less digits than its factorization.

21206293 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1247446.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 21206293 is about 4605.0290987137. The cubic root of 21206293 is about 276.7928830086.

The spelling of 21206293 in words is "twenty-one million, two hundred six thousand, two hundred ninety-three".