1661155650 has 288 divisors, whose sum is σ = 5615640576. Its totient is φ = 342000000.

The previous prime is 1661155597. The next prime is 1661155651. The reversal of 1661155650 is 565511661.

It is not an unprimeable number, because it can be changed into a prime (1661155651) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 6618025 + ... + 6618275.

It is an arithmetic number, because the mean of its divisors is an integer number (19498752).

Almost surely, 2^1661155650 is an apocalyptic number.

1661155650 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661155650, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2807820288).

1661155650 is an abundant number, since it is smaller than the sum of its proper divisors (3954484926).

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

1661155650 is a wasteful number, since it uses less digits than its factorization.

1661155650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478 (or 470 counting only the distinct ones).

The product of its (nonzero) digits is 27000, while the sum is 36.

The square root of 1661155650 is about 40757.2772643120. The cubic root of 1661155650 is about 1184.3228519262.

The spelling of 1661155650 in words is "one billion, six hundred sixty-one million, one hundred fifty-five thousand, six hundred fifty".