261629681961984 has 528 divisors, whose sum is σ = 823983030201600. Its totient is φ = 72297224110080.

The previous prime is 261629681961971. The next prime is 261629681962067. The reversal of 261629681961984 is 489169186926162.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 53295919722 + ... + 53295924630.

Almost surely, 2^{261629681961984} is an apocalyptic number.

261629681961984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261629681961984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (411991515100800).

261629681961984 is an abundant number, since it is smaller than the sum of its proper divisors (562353348239616).

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

261629681961984 is a wasteful number, since it uses less digits than its factorization.

261629681961984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7580 (or 7531 counting only the distinct ones).

The product of its digits is 967458816, while the sum is 78.

The spelling of 261629681961984 in words is "two hundred sixty-one trillion, six hundred twenty-nine billion, six hundred eighty-one million, nine hundred sixty-one thousand, nine hundred eighty-four".