15778261664 has 48 divisors (see below), whose sum is σ = 33937535520. Its totient is φ = 7161327360.

The previous prime is 15778261657. The next prime is 15778261693. The reversal of 15778261664 is 46616287751.

It is a super-2 number, since 2×15778261664² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 207602 + ... + 273230.

It is an arithmetic number, because the mean of its divisors is an integer number (707031990).

Almost surely, 2^15778261664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 15778261664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (16968767760).

15778261664 is an abundant number, since it is smaller than the sum of its proper divisors (18159273856).

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

15778261664 is a wasteful number, since it uses less digits than its factorization.

15778261664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66333 (or 66325 counting only the distinct ones).

The product of its digits is 3386880, while the sum is 53.

The spelling of 15778261664 in words is "fifteen billion, seven hundred seventy-eight million, two hundred sixty-one thousand, six hundred sixty-four".