21157029 has 6 divisors (see below), whose sum is σ = 30560166. Its totient is φ = 14104680.

The previous prime is 21156953. The next prime is 21157039. The reversal of 21157029 is 92075112.

It can be written as a sum of positive squares in only one way, i.e., 14516100 + 6640929 = 3810^2 + 2577^2 .

It is not a de Polignac number, because 21157029 - 2⁷ = 21156901 is a prime.

It is a super-2 number, since 2×21157029² = 895239752213682, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21156993 and 21157011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21157039) 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 5 ways as a sum of consecutive naturals, for example, 1175382 + ... + 1175399.

It is an arithmetic number, because the mean of its divisors is an integer number (5093361).

Almost surely, 2^21157029 is an apocalyptic number.

It is an amenable number.

21157029 is a deficient number, since it is larger than the sum of its proper divisors (9403137).

21157029 is a wasteful number, since it uses less digits than its factorization.

21157029 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2350787 (or 2350784 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 21157029 is about 4599.6770538811. The cubic root of 21157029 is about 276.5783791132.

The spelling of 21157029 in words is "twenty-one million, one hundred fifty-seven thousand, twenty-nine".