661035021 has 8 divisors (see below), whose sum is σ = 933225984. Its totient is φ = 414767040.

The previous prime is 661035017. The next prime is 661035047. The reversal of 661035021 is 120530166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 661035021 - 2² = 661035017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 661034982 and 661035000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661035071) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6480685 + ... + 6480786.

It is an arithmetic number, because the mean of its divisors is an integer number (116653248).

Almost surely, 2^661035021 is an apocalyptic number.

It is an amenable number.

661035021 is a deficient number, since it is larger than the sum of its proper divisors (272190963).

661035021 is a wasteful number, since it uses less digits than its factorization.

661035021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12961491.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 661035021 is about 25710.6013348580. The cubic root of 661035021 is about 871.1136577308.

Adding to 661035021 its reverse (120530166), we get a palindrome (781565187).

It can be divided in two parts, 66 and 1035021, that multiplied together give a palindrome (68311386).

The spelling of 661035021 in words is "six hundred sixty-one million, thirty-five thousand, twenty-one".