19072721 has 2 divisors, whose sum is σ = 19072722. Its totient is φ = 19072720.

The previous prime is 19072717. The next prime is 19072771. The reversal of 19072721 is 12727091.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11316496 + 7756225 = 3364^2 + 2785^2 .

It is a cyclic number.

It is not a de Polignac number, because 19072721 - 2² = 19072717 is a prime.

It is not a weakly prime, because it can be changed into another prime (19072771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9536360 + 9536361.

It is an arithmetic number, because the mean of its divisors is an integer number (9536361).

Almost surely, 2^19072721 is an apocalyptic number.

It is an amenable number.

19072721 is a deficient number, since it is larger than the sum of its proper divisors (1).

19072721 is an equidigital number, since it uses as much as digits as its factorization.

19072721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1764, while the sum is 29.

The square root of 19072721 is about 4367.2326477988. The cubic root of 19072721 is about 267.1801680169.

The spelling of 19072721 in words is "nineteen million, seventy-two thousand, seven hundred twenty-one".