1390929781 has 4 divisors (see below), whose sum is σ = 1401882112. Its totient is φ = 1379977452.

The previous prime is 1390929767. The next prime is 1390929821. The reversal of 1390929781 is 1879290931.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1390929781 - 2⁷ = 1390929653 is a prime.

It is a super-2 number, since 2×1390929781² = 3869371311345415922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1390929481) 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, 5475975 + ... + 5476228.

It is an arithmetic number, because the mean of its divisors is an integer number (350470528).

Almost surely, 2^1390929781 is an apocalyptic number.

It is an amenable number.

1390929781 is a deficient number, since it is larger than the sum of its proper divisors (10952331).

1390929781 is a wasteful number, since it uses less digits than its factorization.

1390929781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10952330.

The product of its (nonzero) digits is 244944, while the sum is 49.

The square root of 1390929781 is about 37295.1710144893. The cubic root of 1390929781 is about 1116.2678121778.

The spelling of 1390929781 in words is "one billion, three hundred ninety million, nine hundred twenty-nine thousand, seven hundred eighty-one".