21100004557 has 2 divisors, whose sum is σ = 21100004558. Its totient is φ = 21100004556.

The previous prime is 21100004543. The next prime is 21100004587. The reversal of 21100004557 is 75540000112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15352696836 + 5747307721 = 123906^2 + 75811^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100004557 - 2²³ = 21091615949 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21100004587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550002278 + 10550002279.

It is an arithmetic number, because the mean of its divisors is an integer number (10550002279).

Almost surely, 2^21100004557 is an apocalyptic number.

It is an amenable number.

21100004557 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100004557 is an equidigital number, since it uses as much as digits as its factorization.

21100004557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1400, while the sum is 25.

Adding to 21100004557 its reverse (75540000112), we get a palindrome (96640004669).

The spelling of 21100004557 in words is "twenty-one billion, one hundred million, four thousand, five hundred fifty-seven".