19912621 has 2 divisors, whose sum is σ = 19912622. Its totient is φ = 19912620.

The previous prime is 19912609. The next prime is 19912637. The reversal of 19912621 is 12621991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19900521 + 12100 = 4461^2 + 110^2 .

It is a cyclic number.

It is not a de Polignac number, because 19912621 - 2⁷ = 19912493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19912691) 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, 9956310 + 9956311.

It is an arithmetic number, because the mean of its divisors is an integer number (9956311).

Almost surely, 2^19912621 is an apocalyptic number.

It is an amenable number.

19912621 is a deficient number, since it is larger than the sum of its proper divisors (1).

19912621 is an equidigital number, since it uses as much as digits as its factorization.

19912621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1944, while the sum is 31.

The square root of 19912621 is about 4462.3559920741. The cubic root of 19912621 is about 271.0458794071.

The spelling of 19912621 in words is "nineteen million, nine hundred twelve thousand, six hundred twenty-one".