661373401 has 4 divisors (see below), whose sum is σ = 712248292. Its totient is φ = 610498512.

The previous prime is 661373399. The next prime is 661373429. The reversal of 661373401 is 104373166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 444577225 + 216796176 = 21085^2 + 14724^2 .

It is not a de Polignac number, because 661373401 - 2¹ = 661373399 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661073401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25437426 + ... + 25437451.

It is an arithmetic number, because the mean of its divisors is an integer number (178062073).

Almost surely, 2^661373401 is an apocalyptic number.

It is an amenable number.

661373401 is a deficient number, since it is larger than the sum of its proper divisors (50874891).

661373401 is a wasteful number, since it uses less digits than its factorization.

661373401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50874890.

The product of its (nonzero) digits is 9072, while the sum is 31.

The square root of 661373401 is about 25717.1810469188. The cubic root of 661373401 is about 871.2622717214.

The spelling of 661373401 in words is "six hundred sixty-one million, three hundred seventy-three thousand, four hundred one".