251021061661071 has 16 divisors (see below), whose sum is σ = 368822835979136. Its totient is φ = 150882069262176.

The previous prime is 251021061661067. The next prime is 251021061661087. The reversal of 251021061661071 is 170166160120152.

It is not a de Polignac number, because 251021061661071 - 2² = 251021061661067 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251021061661171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 74842294585 + ... + 74842297938.

It is an arithmetic number, because the mean of its divisors is an integer number (23051427248696).

Almost surely, 2^{251021061661071} is an apocalyptic number.

251021061661071 is a deficient number, since it is larger than the sum of its proper divisors (117801774318065).

251021061661071 is a wasteful number, since it uses less digits than its factorization.

251021061661071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149684592582.

The product of its (nonzero) digits is 30240, while the sum is 39.

The spelling of 251021061661071 in words is "two hundred fifty-one trillion, twenty-one billion, sixty-one million, six hundred sixty-one thousand, seventy-one".