1661645020 has 48 divisors (see below), whose sum is σ = 4014763200. Its totient is φ = 565876224.

The previous prime is 1661644993. The next prime is 1661645047. The reversal of 1661645020 is 205461661.

It is an interprime number because it is at equal distance from previous prime (1661644993) and next prime (1661645047).

It is a super-2 number, since 2×1661645020² = 5522128344981600800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18969 + ... + 60688.

It is an arithmetic number, because the mean of its divisors is an integer number (83640900).

Almost surely, 2^1661645020 is an apocalyptic number.

1661645020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1661645020 is an abundant number, since it is smaller than the sum of its proper divisors (2353118180).

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

1661645020 is a wasteful number, since it uses less digits than its factorization.

1661645020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79822 (or 79820 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 1661645020 is about 40763.2802899865. The cubic root of 1661645020 is about 1184.4391394778.

The spelling of 1661645020 in words is "one billion, six hundred sixty-one million, six hundred forty-five thousand, twenty".