19221721 has 8 divisors (see below), whose sum is σ = 20301120. Its totient is φ = 18162672.

The previous prime is 19221707. The next prime is 19221733. The reversal of 19221721 is 12712291.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19221721 - 2⁷ = 19221593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19221701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3126 + ... + 6943.

It is an arithmetic number, because the mean of its divisors is an integer number (2537640).

Almost surely, 2^19221721 is an apocalyptic number.

It is an amenable number.

19221721 is a deficient number, since it is larger than the sum of its proper divisors (1079399).

19221721 is a wasteful number, since it uses less digits than its factorization.

19221721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10175.

The product of its digits is 504, while the sum is 25.

The square root of 19221721 is about 4384.2583181195. The cubic root of 19221721 is about 267.8741194303.

The spelling of 19221721 in words is "nineteen million, two hundred twenty-one thousand, seven hundred twenty-one".