661088407821 has 8 divisors (see below), whose sum is σ = 881466032064. Its totient is φ = 440718194400.

The previous prime is 661088407807. The next prime is 661088407831. The reversal of 661088407821 is 128704880166.

661088407821 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 661088407821 - 2¹⁷ = 661088276749 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661088407801) 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, 1641105 + ... + 2003846.

It is an arithmetic number, because the mean of its divisors is an integer number (110183254008).

Almost surely, 2^661088407821 is an apocalyptic number.

It is an amenable number.

661088407821 is a deficient number, since it is larger than the sum of its proper divisors (220377624243).

661088407821 is a wasteful number, since it uses less digits than its factorization.

661088407821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3705411.

The product of its (nonzero) digits is 1032192, while the sum is 51.

The spelling of 661088407821 in words is "six hundred sixty-one billion, eighty-eight million, four hundred seven thousand, eight hundred twenty-one".