21621272953997 has 2 divisors, whose sum is σ = 21621272953998. Its totient is φ = 21621272953996.

The previous prime is 21621272953937. The next prime is 21621272954003. The reversal of 21621272953997 is 79935927212612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20633861087401 + 987411866596 = 4542451^2 + 993686^2 .

It is a cyclic number.

It is not a de Polignac number, because 21621272953997 - 2⁶ = 21621272953933 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21621272953937) 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, 10810636476998 + 10810636476999.

It is an arithmetic number, because the mean of its divisors is an integer number (10810636476999).

Almost surely, 2^{21621272953997} is an apocalyptic number.

It is an amenable number.

21621272953997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21621272953997 is an equidigital number, since it uses as much as digits as its factorization.

21621272953997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51438240, while the sum is 65.

The spelling of 21621272953997 in words is "twenty-one trillion, six hundred twenty-one billion, two hundred seventy-two million, nine hundred fifty-three thousand, nine hundred ninety-seven".