661237447 has 4 divisors (see below), whose sum is σ = 712101880. Its totient is φ = 610373016.

The previous prime is 661237403. The next prime is 661237459. The reversal of 661237447 is 744732166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 744732166 = 2 ⋅372366083.

It is a cyclic number.

It is not a de Polignac number, because 661237447 - 2²³ = 652848839 is a prime.

It is a super-2 number, since 2×661237447² = 874469922630155618, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661237477) 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, 25432197 + ... + 25432222.

It is an arithmetic number, because the mean of its divisors is an integer number (178025470).

Almost surely, 2^661237447 is an apocalyptic number.

661237447 is a deficient number, since it is larger than the sum of its proper divisors (50864433).

661237447 is a wasteful number, since it uses less digits than its factorization.

661237447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50864432.

The product of its digits is 169344, while the sum is 40.

The square root of 661237447 is about 25714.5376586864. The cubic root of 661237447 is about 871.2025678244.

The spelling of 661237447 in words is "six hundred sixty-one million, two hundred thirty-seven thousand, four hundred forty-seven".