21375557 has 8 divisors (see below), whose sum is σ = 24565632. Its totient is φ = 18219600.

The previous prime is 21375521. The next prime is 21375569. The reversal of 21375557 is 75557312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21375557 - 2⁶ = 21375493 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21375517) 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, 7169 + ... + 9702.

It is an arithmetic number, because the mean of its divisors is an integer number (3070704).

Almost surely, 2^21375557 is an apocalyptic number.

It is an amenable number.

21375557 is a deficient number, since it is larger than the sum of its proper divisors (3190075).

21375557 is a wasteful number, since it uses less digits than its factorization.

21375557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17059.

The product of its digits is 36750, while the sum is 35.

The square root of 21375557 is about 4623.3707400554. The cubic root of 21375557 is about 277.5273657508.

The spelling of 21375557 in words is "twenty-one million, three hundred seventy-five thousand, five hundred fifty-seven".