1390426778 has 16 divisors (see below), whose sum is σ = 2254079016. Its totient is φ = 639448320.

The previous prime is 1390426771. The next prime is 1390426789. The reversal of 1390426778 is 8776240931.

It can be written as a sum of positive squares in 4 ways, for example, as 659102929 + 731323849 = 25673^2 + 27043^2 .

It is a super-2 number, since 2×1390426778² = 3866573249958922568, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1390426771) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 87851 + ... + 102462.

Almost surely, 2^1390426778 is an apocalyptic number.

1390426778 is a deficient number, since it is larger than the sum of its proper divisors (863652238).

1390426778 is a wasteful number, since it uses less digits than its factorization.

1390426778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 190609.

The product of its (nonzero) digits is 508032, while the sum is 47.

The square root of 1390426778 is about 37288.4268641089. The cubic root of 1390426778 is about 1116.1332370269.

The spelling of 1390426778 in words is "one billion, three hundred ninety million, four hundred twenty-six thousand, seven hundred seventy-eight".