613978921 has 2 divisors, whose sum is σ = 613978922. Its totient is φ = 613978920.

The previous prime is 613978909. The next prime is 613978933. The reversal of 613978921 is 129879316.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (613978909) and next prime (613978933).

It can be written as a sum of positive squares in only one way, i.e., 601475625 + 12503296 = 24525^2 + 3536^2 .

It is a cyclic number.

It is not a de Polignac number, because 613978921 - 2²¹ = 611881769 is a prime.

It is not a weakly prime, because it can be changed into another prime (613978991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 306989460 + 306989461.

It is an arithmetic number, because the mean of its divisors is an integer number (306989461).

Almost surely, 2^613978921 is an apocalyptic number.

It is an amenable number.

613978921 is a deficient number, since it is larger than the sum of its proper divisors (1).

613978921 is an equidigital number, since it uses as much as digits as its factorization.

613978921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 163296, while the sum is 46.

The square root of 613978921 is about 24778.5980434729. The cubic root of 613978921 is about 849.9325994999.

The spelling of 613978921 in words is "six hundred thirteen million, nine hundred seventy-eight thousand, nine hundred twenty-one".