51249073661 has 4 divisors (see below), whose sum is σ = 51250073532. Its totient is φ = 51248073792.

The previous prime is 51249073607. The next prime is 51249073679. The reversal of 51249073661 is 16637094215.

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 16422422500 + 34826651161 = 128150^2 + 186619^2 .

It is a cyclic number.

It is not a de Polignac number, because 51249073661 - 2³⁰ = 50175331837 is a prime.

It is a super-2 number, since 2×51249073661² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51249073691) 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, 418646 + ... + 527031.

It is an arithmetic number, because the mean of its divisors is an integer number (12812518383).

Almost surely, 2^51249073661 is an apocalyptic number.

It is an amenable number.

51249073661 is a deficient number, since it is larger than the sum of its proper divisors (999871).

51249073661 is an equidigital number, since it uses as much as digits as its factorization.

51249073661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 999870.

The product of its (nonzero) digits is 272160, while the sum is 44.

The spelling of 51249073661 in words is "fifty-one billion, two hundred forty-nine million, seventy-three thousand, six hundred sixty-one".