19720001 has 24 divisors (see below), whose sum is σ = 24042600. Its totient is φ = 16111872.

The previous prime is 19719943. The next prime is 19720021. The reversal of 19720001 is 10002791.

19720001 is a nontrivial binomial coefficient, being equal to C(149, 4).

It can be written as a sum of positive squares in 4 ways, for example, as 3519376 + 16200625 = 1876^2 + 4025^2 .

It is not a de Polignac number, because 19720001 - 2¹⁰ = 19718977 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19720021) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 132275 + ... + 132423.

It is an arithmetic number, because the mean of its divisors is an integer number (1001775).

Almost surely, 2^19720001 is an apocalyptic number.

19720001 is the 3626-th pentagonal number.

It is an amenable number.

19720001 is a deficient number, since it is larger than the sum of its proper divisors (4322599).

19720001 is a wasteful number, since it uses less digits than its factorization.

19720001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 273 (or 266 counting only the distinct ones).

The product of its (nonzero) digits is 126, while the sum is 20.

The square root of 19720001 is about 4440.7207748292. The cubic root of 19720001 is about 270.1690801957.

Adding to 19720001 its reverse (10002791), we get a palindrome (29722792).

The spelling of 19720001 in words is "nineteen million, seven hundred twenty thousand, one".