21191357 has 4 divisors (see below), whose sum is σ = 23117856. Its totient is φ = 19264860.

The previous prime is 21191341. The next prime is 21191369. The reversal of 21191357 is 75319112.

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 not a de Polignac number, because 21191357 - 2⁴ = 21191341 is a prime.

It is a super-2 number, since 2×21191357² = 898147223002898, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21191377) 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, 963233 + ... + 963254.

It is an arithmetic number, because the mean of its divisors is an integer number (5779464).

Almost surely, 2^21191357 is an apocalyptic number.

It is an amenable number.

21191357 is a deficient number, since it is larger than the sum of its proper divisors (1926499).

21191357 is a wasteful number, since it uses less digits than its factorization.

21191357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1926498.

The product of its digits is 1890, while the sum is 29.

The square root of 21191357 is about 4603.4071077844. The cubic root of 21191357 is about 276.7278842293.

The spelling of 21191357 in words is "twenty-one million, one hundred ninety-one thousand, three hundred fifty-seven".