661626554 has 4 divisors (see below), whose sum is σ = 992439834. Its totient is φ = 330813276.

The previous prime is 661626551. The next prime is 661626593. The reversal of 661626554 is 455626166.

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

It can be written as a sum of positive squares in only one way, i.e., 509720929 + 151905625 = 22577^2 + 12325^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (661626551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165406637 + ... + 165406640.

Almost surely, 2^661626554 is an apocalyptic number.

661626554 is a deficient number, since it is larger than the sum of its proper divisors (330813280).

661626554 is a wasteful number, since it uses less digits than its factorization.

661626554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330813279.

The product of its digits is 259200, while the sum is 41.

The square root of 661626554 is about 25722.1024412858. The cubic root of 661626554 is about 871.3734215005.

The spelling of 661626554 in words is "six hundred sixty-one million, six hundred twenty-six thousand, five hundred fifty-four".