2656699978 has 8 divisors (see below), whose sum is σ = 4000556772. Its totient is φ = 1323181056.

The previous prime is 2656699951. The next prime is 2656699979. The reversal of 2656699978 is 8799966562.

It can be written as a sum of positive squares in 2 ways, for example, as 1615798809 + 1040901169 = 40197^2 + 32263^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (2656699979) 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, 2583825 + ... + 2584852.

Almost surely, 2^2656699978 is an apocalyptic number.

2656699978 is a deficient number, since it is larger than the sum of its proper divisors (1343856794).

2656699978 is a wasteful number, since it uses less digits than its factorization.

2656699978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5168936.

The product of its digits is 88179840, while the sum is 67.

The square root of 2656699978 is about 51543.1855631761. The cubic root of 2656699978 is about 1384.9927628897.

The spelling of 2656699978 in words is "two billion, six hundred fifty-six million, six hundred ninety-nine thousand, nine hundred seventy-eight".