21102111977 has 2 divisors, whose sum is σ = 21102111978. Its totient is φ = 21102111976.

The previous prime is 21102111929. The next prime is 21102112001. The reversal of 21102111977 is 77911120112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11618468521 + 9483643456 = 107789^2 + 97384^2 .

It is a cyclic number.

It is not a de Polignac number, because 21102111977 - 2¹² = 21102107881 is a prime.

It is not a weakly prime, because it can be changed into another prime (21102111907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551055988 + 10551055989.

It is an arithmetic number, because the mean of its divisors is an integer number (10551055989).

Almost surely, 2^21102111977 is an apocalyptic number.

It is an amenable number.

21102111977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21102111977 is an equidigital number, since it uses as much as digits as its factorization.

21102111977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1764, while the sum is 32.

The spelling of 21102111977 in words is "twenty-one billion, one hundred two million, one hundred eleven thousand, nine hundred seventy-seven".