672100021 has 2 divisors, whose sum is σ = 672100022. Its totient is φ = 672100020.

The previous prime is 672100007. The next prime is 672100031. The reversal of 672100021 is 120001276.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 375778225 + 296321796 = 19385^2 + 17214^2 .

It is a cyclic number.

It is not a de Polignac number, because 672100021 - 2⁷ = 672099893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (672100031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 336050010 + 336050011.

It is an arithmetic number, because the mean of its divisors is an integer number (336050011).

Almost surely, 2^672100021 is an apocalyptic number.

It is an amenable number.

672100021 is a deficient number, since it is larger than the sum of its proper divisors (1).

672100021 is an equidigital number, since it uses as much as digits as its factorization.

672100021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 672100021 is about 25924.8919187718. The cubic root of 672100021 is about 875.9472825562.

Adding to 672100021 its reverse (120001276), we get a palindrome (792101297).

The spelling of 672100021 in words is "six hundred seventy-two million, one hundred thousand, twenty-one".