21858057 has 24 divisors (see below), whose sum is σ = 34192704. Its totient is φ = 13375584.

The previous prime is 21858029. The next prime is 21858127. The reversal of 21858057 is 75085812.

21858057 is a `hidden beast` number, since 21 + 8 + 580 + 57 = 666.

It is not a de Polignac number, because 21858057 - 2⁶ = 21857993 is a prime.

It is a super-3 number, since 3×21858057³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21858017) 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 23 ways as a sum of consecutive naturals, for example, 26148 + ... + 26970.

It is an arithmetic number, because the mean of its divisors is an integer number (1424696).

Almost surely, 2^21858057 is an apocalyptic number.

It is an amenable number.

21858057 is a deficient number, since it is larger than the sum of its proper divisors (12334647).

21858057 is a wasteful number, since it uses less digits than its factorization.

21858057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1069 (or 1066 counting only the distinct ones).

The product of its (nonzero) digits is 22400, while the sum is 36.

The square root of 21858057 is about 4675.2600997164. The cubic root of 21858057 is about 279.6000113590.

It can be divided in two parts, 2185805 and 7, that added together give a palindrome (2185812).

The spelling of 21858057 in words is "twenty-one million, eight hundred fifty-eight thousand, fifty-seven".