7851621761 has 4 divisors (see below), whose sum is σ = 7854206724. Its totient is φ = 7849036800.

The previous prime is 7851621637. The next prime is 7851621763. The reversal of 7851621761 is 1671261587.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7416482161 + 435139600 = 86119^2 + 20860^2 .

It is a cyclic number.

It is not a de Polignac number, because 7851621761 - 2¹⁸ = 7851359617 is a prime.

It is a super-2 number, since 2×7851621761² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7851621763) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1287920 + ... + 1294001.

It is an arithmetic number, because the mean of its divisors is an integer number (1963551681).

Almost surely, 2^7851621761 is an apocalyptic number.

It is an amenable number.

7851621761 is a deficient number, since it is larger than the sum of its proper divisors (2584963).

7851621761 is a wasteful number, since it uses less digits than its factorization.

7851621761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2584962.

The product of its digits is 141120, while the sum is 44.

The square root of 7851621761 is about 88609.3773874978. The cubic root of 7851621761 is about 1987.5579043874.

The spelling of 7851621761 in words is "seven billion, eight hundred fifty-one million, six hundred twenty-one thousand, seven hundred sixty-one".