21202057 has 4 divisors (see below), whose sum is σ = 21308800. Its totient is φ = 21095316.

The previous prime is 21202039. The next prime is 21202079. The reversal of 21202057 is 75020212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21202057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21202037) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53073 + ... + 53470.

It is an arithmetic number, because the mean of its divisors is an integer number (5327200).

Almost surely, 2^21202057 is an apocalyptic number.

It is an amenable number.

21202057 is a deficient number, since it is larger than the sum of its proper divisors (106743).

21202057 is a wasteful number, since it uses less digits than its factorization.

21202057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106742.

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 21202057 is about 4604.5691437962. The cubic root of 21202057 is about 276.7744518016.

Adding to 21202057 its reverse (75020212), we get a palindrome (96222269).

It can be divided in two parts, 2120205 and 7, that added together give a palindrome (2120212).

The spelling of 21202057 in words is "twenty-one million, two hundred two thousand, fifty-seven".