21621960377 has 2 divisors, whose sum is σ = 21621960378. Its totient is φ = 21621960376.

The previous prime is 21621960319. The next prime is 21621960403. The reversal of 21621960377 is 77306912612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13591829056 + 8030131321 = 116584^2 + 89611^2 .

It is a cyclic number.

It is not a de Polignac number, because 21621960377 - 2¹⁶ = 21621894841 is a prime.

It is not a weakly prime, because it can be changed into another prime (21621960307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10810980188 + 10810980189.

It is an arithmetic number, because the mean of its divisors is an integer number (10810980189).

Almost surely, 2^21621960377 is an apocalyptic number.

It is an amenable number.

21621960377 is a deficient number, since it is larger than the sum of its proper divisors (1).

21621960377 is an equidigital number, since it uses as much as digits as its factorization.

21621960377 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 190512, while the sum is 44.

The spelling of 21621960377 in words is "twenty-one billion, six hundred twenty-one million, nine hundred sixty thousand, three hundred seventy-seven".