21221010077 has 2 divisors, whose sum is σ = 21221010078. Its totient is φ = 21221010076.

The previous prime is 21221010017. The next prime is 21221010113. The reversal of 21221010077 is 77001012212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21219457561 + 1552516 = 145669^2 + 1246^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221010077 - 2³² = 16926042781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221010017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610505038 + 10610505039.

It is an arithmetic number, because the mean of its divisors is an integer number (10610505039).

Almost surely, 2^21221010077 is an apocalyptic number.

It is an amenable number.

21221010077 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221010077 is an equidigital number, since it uses as much as digits as its factorization.

21221010077 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 392, while the sum is 23.

Adding to 21221010077 its reverse (77001012212), we get a palindrome (98222022289).

The spelling of 21221010077 in words is "twenty-one billion, two hundred twenty-one million, ten thousand, seventy-seven".