251576978641 has 4 divisors (see below), whose sum is σ = 260252046900. Its totient is φ = 242901910384.

The previous prime is 251576978591. The next prime is 251576978689. The reversal of 251576978641 is 146879675152.

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 82754604241 + 168822374400 = 287671^2 + 410880^2 .

It is a cyclic number.

It is not a de Polignac number, because 251576978641 - 2⁹ = 251576978129 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 251576978641.

It is not an unprimeable number, because it can be changed into a prime (251576978041) 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, 4337534086 + ... + 4337534143.

It is an arithmetic number, because the mean of its divisors is an integer number (65063011725).

Almost surely, 2^251576978641 is an apocalyptic number.

It is an amenable number.

251576978641 is a deficient number, since it is larger than the sum of its proper divisors (8675068259).

251576978641 is an equidigital number, since it uses as much as digits as its factorization.

251576978641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8675068258.

The product of its digits is 25401600, while the sum is 61.

The spelling of 251576978641 in words is "two hundred fifty-one billion, five hundred seventy-six million, nine hundred seventy-eight thousand, six hundred forty-one".