21021202001957 has 2 divisors, whose sum is σ = 21021202001958. Its totient is φ = 21021202001956.

The previous prime is 21021202001953. The next prime is 21021202001999. The reversal of 21021202001957 is 75910020212012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21015384736516 + 5817265441 = 4584254^2 + 76271^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021202001957 - 2² = 21021202001953 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021202001953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510601000978 + 10510601000979.

It is an arithmetic number, because the mean of its divisors is an integer number (10510601000979).

Almost surely, 2^{21021202001957} is an apocalyptic number.

It is an amenable number.

21021202001957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021202001957 is an equidigital number, since it uses as much as digits as its factorization.

21021202001957 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5040, while the sum is 32.

Adding to 21021202001957 its reverse (75910020212012), we get a palindrome (96931222213969).

The spelling of 21021202001957 in words is "twenty-one trillion, twenty-one billion, two hundred two million, one thousand, nine hundred fifty-seven".