21011021999977 has 2 divisors, whose sum is σ = 21011021999978. Its totient is φ = 21011021999976.

The previous prime is 21011021999939. The next prime is 21011022000049. The reversal of 21011021999977 is 77999912011012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20264933752281 + 746088247696 = 4501659^2 + 863764^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21011021999977 is a prime.

It is not a weakly prime, because it can be changed into another prime (21011021999917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505510999988 + 10505510999989.

It is an arithmetic number, because the mean of its divisors is an integer number (10505510999989).

Almost surely, 2^{21011021999977} is an apocalyptic number.

It is an amenable number.

21011021999977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011021999977 is an equidigital number, since it uses as much as digits as its factorization.

21011021999977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1285956, while the sum is 58.

The spelling of 21011021999977 in words is "twenty-one trillion, eleven billion, twenty-one million, nine hundred ninety-nine thousand, nine hundred seventy-seven".