21910557 has 4 divisors (see below), whose sum is σ = 29214080. Its totient is φ = 14607036.

The previous prime is 21910531. The next prime is 21910561. The reversal of 21910557 is 75501912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21910557 - 2¹² = 21906461 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 (21910517) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3651757 + ... + 3651762.

It is an arithmetic number, because the mean of its divisors is an integer number (7303520).

Almost surely, 2^21910557 is an apocalyptic number.

It is an amenable number.

21910557 is a deficient number, since it is larger than the sum of its proper divisors (7303523).

21910557 is an equidigital number, since it uses as much as digits as its factorization.

21910557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7303522.

The product of its (nonzero) digits is 3150, while the sum is 30.

The square root of 21910557 is about 4680.8713932344. The cubic root of 21910557 is about 279.8236857681.

The spelling of 21910557 in words is "twenty-one million, nine hundred ten thousand, five hundred fifty-seven".