7638107921 has 2 divisors, whose sum is σ = 7638107922. Its totient is φ = 7638107920.

The previous prime is 7638107849. The next prime is 7638107941. The reversal of 7638107921 is 1297018367.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6058442896 + 1579665025 = 77836^2 + 39745^2 .

It is a cyclic number.

It is not a de Polignac number, because 7638107921 - 2¹⁰ = 7638106897 is a prime.

It is a super-2 number, since 2×7638107921² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (7638107941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3819053960 + 3819053961.

It is an arithmetic number, because the mean of its divisors is an integer number (3819053961).

Almost surely, 2^7638107921 is an apocalyptic number.

It is an amenable number.

7638107921 is a deficient number, since it is larger than the sum of its proper divisors (1).

7638107921 is an equidigital number, since it uses as much as digits as its factorization.

7638107921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 127008, while the sum is 44.

The square root of 7638107921 is about 87396.2694913233. The cubic root of 7638107921 is about 1969.3757993035.

The spelling of 7638107921 in words is "seven billion, six hundred thirty-eight million, one hundred seven thousand, nine hundred twenty-one".