251500542421 has 4 divisors (see below), whose sum is σ = 253726211052. Its totient is φ = 249274873792.

The previous prime is 251500542373. The next prime is 251500542457. The reversal of 251500542421 is 124245005152.

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 84309510321 + 167191032100 = 290361^2 + 408890^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251500542421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251500342421) 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, 1112834146 + ... + 1112834371.

It is an arithmetic number, because the mean of its divisors is an integer number (63431552763).

Almost surely, 2^251500542421 is an apocalyptic number.

It is an amenable number.

251500542421 is a deficient number, since it is larger than the sum of its proper divisors (2225668631).

251500542421 is a wasteful number, since it uses less digits than its factorization.

251500542421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2225668630.

The product of its (nonzero) digits is 16000, while the sum is 31.

Adding to 251500542421 its reverse (124245005152), we get a palindrome (375745547573).

The spelling of 251500542421 in words is "two hundred fifty-one billion, five hundred million, five hundred forty-two thousand, four hundred twenty-one".