251662666640 has 80 divisors (see below), whose sum is σ = 729494916480. Its totient is φ = 78440309760.

The previous prime is 251662666631. The next prime is 251662666649. The reversal of 251662666640 is 46666266152.

It is an interprime number because it is at equal distance from previous prime (251662666631) and next prime (251662666649).

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (251662666649) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20421005 + ... + 20433324.

It is an arithmetic number, because the mean of its divisors is an integer number (9118686456).

Almost surely, 2^251662666640 is an apocalyptic number.

251662666640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

251662666640 is an abundant number, since it is smaller than the sum of its proper divisors (477832249840).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

251662666640 is a wasteful number, since it uses less digits than its factorization.

251662666640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40854360 (or 40854354 counting only the distinct ones).

The product of its (nonzero) digits is 3732480, while the sum is 50.

The spelling of 251662666640 in words is "two hundred fifty-one billion, six hundred sixty-two million, six hundred sixty-six thousand, six hundred forty".