661354401 has 4 divisors (see below), whose sum is σ = 881805872. Its totient is φ = 440902932.

The previous prime is 661354399. The next prime is 661354429. The reversal of 661354401 is 104453166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 661354401 - 2¹ = 661354399 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661354471) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110225731 + ... + 110225736.

It is an arithmetic number, because the mean of its divisors is an integer number (220451468).

Almost surely, 2^661354401 is an apocalyptic number.

It is an amenable number.

661354401 is a deficient number, since it is larger than the sum of its proper divisors (220451471).

661354401 is a wasteful number, since it uses less digits than its factorization.

661354401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220451470.

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 661354401 is about 25716.8116414146. The cubic root of 661354401 is about 871.2539284055.

The spelling of 661354401 in words is "six hundred sixty-one million, three hundred fifty-four thousand, four hundred one".