661101540 has 48 divisors (see below), whose sum is σ = 2019366720. Its totient is φ = 160266880.

The previous prime is 661101517. The next prime is 661101541. The reversal of 661101540 is 45101166.

It is a self number, because there is not a number n which added to its sum of digits gives 661101540.

It is not an unprimeable number, because it can be changed into a prime (661101541) 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, 500175 + ... + 501494.

It is an arithmetic number, because the mean of its divisors is an integer number (42070140).

Almost surely, 2^661101540 is an apocalyptic number.

661101540 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661101540 is an abundant number, since it is smaller than the sum of its proper divisors (1358265180).

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

661101540 is a wasteful number, since it uses less digits than its factorization.

661101540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1001692 (or 1001690 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 661101540 is about 25711.8949126664. The cubic root of 661101540 is about 871.1428763874.

It can be divided in two parts, 661 and 101540, that added together give a palindrome (102201).

The spelling of 661101540 in words is "six hundred sixty-one million, one hundred one thousand, five hundred forty".