21151357 has 4 divisors (see below), whose sum is σ = 21233916. Its totient is φ = 21068800.

The previous prime is 21151343. The next prime is 21151433. The reversal of 21151357 is 75315112.

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 18481401 + 2669956 = 4299^2 + 1634^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21151357 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 (21151307) 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, 40894 + ... + 41407.

It is an arithmetic number, because the mean of its divisors is an integer number (5308479).

Almost surely, 2^21151357 is an apocalyptic number.

It is an amenable number.

21151357 is a deficient number, since it is larger than the sum of its proper divisors (82559).

21151357 is an equidigital number, since it uses as much as digits as its factorization.

21151357 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82558.

The product of its digits is 1050, while the sum is 25.

The square root of 21151357 is about 4599.0604475262. The cubic root of 21151357 is about 276.5536608855.

Adding to 21151357 its reverse (75315112), we get a palindrome (96466469).

The spelling of 21151357 in words is "twenty-one million, one hundred fifty-one thousand, three hundred fifty-seven".