661556151651630 has 32 divisors (see below), whose sum is σ = 1671299751542400. Its totient is φ = 167129975153952.

The previous prime is 661556151651607. The next prime is 661556151651631. The reversal of 661556151651630 is 36156151655166.

It is a happy number.

It is a super-2 number, since 2×661556151651630² (a number of 30 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661556151651631) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 580312413160 + ... + 580312414299.

It is an arithmetic number, because the mean of its divisors is an integer number (52228117235700).

Almost surely, 2^{661556151651630} is an apocalyptic number.

661556151651630 is an abundant number, since it is smaller than the sum of its proper divisors (1009743599890770).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661556151651630 is a wasteful number, since it uses less digits than its factorization.

661556151651630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1160624827488.

The product of its (nonzero) digits is 14580000, while the sum is 57.

The spelling of 661556151651630 in words is "six hundred sixty-one trillion, five hundred fifty-six billion, one hundred fifty-one million, six hundred fifty-one thousand, six hundred thirty".