661561053 has 4 divisors (see below), whose sum is σ = 882081408. Its totient is φ = 441040700.

The previous prime is 661561051. The next prime is 661561097. The reversal of 661561053 is 350165166.

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 a cyclic number.

It is not a de Polignac number, because 661561053 - 2¹ = 661561051 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 (661561051) 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, 110260173 + ... + 110260178.

It is an arithmetic number, because the mean of its divisors is an integer number (220520352).

Almost surely, 2^661561053 is an apocalyptic number.

It is an amenable number.

661561053 is a deficient number, since it is larger than the sum of its proper divisors (220520355).

661561053 is a wasteful number, since it uses less digits than its factorization.

661561053 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220520354.

The product of its (nonzero) digits is 16200, while the sum is 33.

The square root of 661561053 is about 25720.8291662613. The cubic root of 661561053 is about 871.3446652413.

The spelling of 661561053 in words is "six hundred sixty-one million, five hundred sixty-one thousand, fifty-three".