21157783 has 8 divisors (see below), whose sum is σ = 21473856. Its totient is φ = 20844000.

The previous prime is 21157757. The next prime is 21157793. The reversal of 21157783 is 38775112.

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 21157783 - 2⁵ = 21157751 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 (21157753) 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, 26985 + ... + 27757.

It is an arithmetic number, because the mean of its divisors is an integer number (2684232).

Almost surely, 2^21157783 is an apocalyptic number.

21157783 is a deficient number, since it is larger than the sum of its proper divisors (316073).

21157783 is a wasteful number, since it uses less digits than its factorization.

21157783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1145.

The product of its digits is 11760, while the sum is 34.

The square root of 21157783 is about 4599.7590154268. The cubic root of 21157783 is about 276.5816646662.

The spelling of 21157783 in words is "twenty-one million, one hundred fifty-seven thousand, seven hundred eighty-three".