1661499840 has 1008 divisors, whose sum is σ = 7630485120. Its totient is φ = 301916160.

The previous prime is 1661499787. The next prime is 1661499863. The reversal of 1661499840 is 489941661.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 1661499840.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 87447351 + ... + 87447369.

Almost surely, 2^1661499840 is an apocalyptic number.

1661499840 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 1661499840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3815242560).

1661499840 is an abundant number, since it is smaller than the sum of its proper divisors (5968985280).

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

1661499840 is a wasteful number, since it uses less digits than its factorization.

1661499840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90 (or 60 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 48.

The square root of 1661499840 is about 40761.4994817413. The cubic root of 1661499840 is about 1184.4046431643.

It can be divided in two parts, 1661 and 499840, that added together give a triangular number (501501 = T₁₀₀₁).

The spelling of 1661499840 in words is "one billion, six hundred sixty-one million, four hundred ninety-nine thousand, eight hundred forty".