1661811370 has 32 divisors (see below), whose sum is σ = 3190380048. Its totient is φ = 621047808.

The previous prime is 1661811311. The next prime is 1661811379. The reversal of 1661811370 is 731181661.

It can be written as a sum of positive squares in 8 ways, for example, as 1514844241 + 146967129 = 38921^2 + 12123^2 .

It is a super-2 number, since 2×1661811370² = 5523234058922553800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is not an unprimeable number, because it can be changed into a prime (1661811379) 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, 12387 + ... + 58966.

Almost surely, 2^1661811370 is an apocalyptic number.

1661811370 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1661811370 is a deficient number, since it is larger than the sum of its proper divisors (1528568678).

1661811370 is a wasteful number, since it uses less digits than its factorization.

1661811370 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71514.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 1661811370 is about 40765.3206782432. The cubic root of 1661811370 is about 1184.4786635385.

The spelling of 1661811370 in words is "one billion, six hundred sixty-one million, eight hundred eleven thousand, three hundred seventy".