161226780 has 384 divisors, whose sum is σ = 596090880. Its totient is φ = 31933440.

The previous prime is 161226743. The next prime is 161226787. The reversal of 161226780 is 87622161.

161226780 = T₁ + T₂ + ... + T₉₈₈.

161226780 is a nontrivial binomial coefficient, being equal to C(990, 3).

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161226787) by changing a digit.

It is the 988-th tetrahedral number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 3749439 + ... + 3749481.

It is an arithmetic number, because the mean of its divisors is an integer number (1552320).

Almost surely, 2^161226780 is an apocalyptic number.

161226780 is a gapful number since it is divisible by the number (10) 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 161226780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (298045440).

161226780 is an abundant number, since it is smaller than the sum of its proper divisors (434864100).

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

161226780 is a wasteful number, since it uses less digits than its factorization.

161226780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121 (or 119 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 161226780 is about 12697.5107796765. The cubic root of 161226780 is about 544.2674893787.

The spelling of 161226780 in words is "one hundred sixty-one million, two hundred twenty-six thousand, seven hundred eighty".