661252466021 has 16 divisors (see below), whose sum is σ = 776736357120. Its totient is φ = 551232190080.

The previous prime is 661252466009. The next prime is 661252466059. The reversal of 661252466021 is 120664252166.

It is not a de Polignac number, because 661252466021 - 2¹⁸ = 661252203877 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661252466021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661252463021) 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, 8662001 + ... + 8738006.

It is an arithmetic number, because the mean of its divisors is an integer number (48546022320).

Almost surely, 2^661252466021 is an apocalyptic number.

661252466021 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

661252466021 is a deficient number, since it is larger than the sum of its proper divisors (115483891099).

661252466021 is a wasteful number, since it uses less digits than its factorization.

661252466021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17400164.

The product of its (nonzero) digits is 207360, while the sum is 41.

The spelling of 661252466021 in words is "six hundred sixty-one billion, two hundred fifty-two million, four hundred sixty-six thousand, twenty-one".