21887827649 has 2 divisors, whose sum is σ = 21887827650. Its totient is φ = 21887827648.

The previous prime is 21887827631. The next prime is 21887827697. The reversal of 21887827649 is 94672878812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17228400049 + 4659427600 = 131257^2 + 68260^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21887827649 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21887827591 and 21887827600.

It is not a weakly prime, because it can be changed into another prime (21887827699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10943913824 + 10943913825.

It is an arithmetic number, because the mean of its divisors is an integer number (10943913825).

Almost surely, 2^21887827649 is an apocalyptic number.

It is an amenable number.

21887827649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21887827649 is an equidigital number, since it uses as much as digits as its factorization.

21887827649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21676032, while the sum is 62.

The spelling of 21887827649 in words is "twenty-one billion, eight hundred eighty-seven million, eight hundred twenty-seven thousand, six hundred forty-nine".