721619401 has 2 divisors, whose sum is σ = 721619402. Its totient is φ = 721619400.

The previous prime is 721619359. The next prime is 721619453. The reversal of 721619401 is 104916127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 698809225 + 22810176 = 26435^2 + 4776^2 .

It is a cyclic number.

It is not a de Polignac number, because 721619401 - 2⁹ = 721618889 is a prime.

It is equal to p_37313545 and since 721619401 and 37313545 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (721614401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360809700 + 360809701.

It is an arithmetic number, because the mean of its divisors is an integer number (360809701).

Almost surely, 2^721619401 is an apocalyptic number.

It is an amenable number.

721619401 is a deficient number, since it is larger than the sum of its proper divisors (1).

721619401 is an equidigital number, since it uses as much as digits as its factorization.

721619401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 721619401 is about 26862.9745374558. The cubic root of 721619401 is about 896.9524083147.

The spelling of 721619401 in words is "seven hundred twenty-one million, six hundred nineteen thousand, four hundred one".