21142557 has 12 divisors (see below), whose sum is σ = 30579744. Its totient is φ = 14076360.

The previous prime is 21142531. The next prime is 21142613. The reversal of 21142557 is 75524112.

It is not a de Polignac number, because 21142557 - 2⁶ = 21142493 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21142557.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21132557) 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 11 ways as a sum of consecutive naturals, for example, 10632 + ... + 12462.

It is an arithmetic number, because the mean of its divisors is an integer number (2548312).

Almost surely, 2^21142557 is an apocalyptic number.

It is an amenable number.

21142557 is a deficient number, since it is larger than the sum of its proper divisors (9437187).

21142557 is a wasteful number, since it uses less digits than its factorization.

21142557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3120 (or 3117 counting only the distinct ones).

The product of its digits is 2800, while the sum is 27.

The square root of 21142557 is about 4598.1036308461. The cubic root of 21142557 is about 276.5153022780.

Adding to 21142557 its reverse (75524112), we get a palindrome (96666669).

The spelling of 21142557 in words is "twenty-one million, one hundred forty-two thousand, five hundred fifty-seven".