1056071991 has 8 divisors (see below), whose sum is σ = 1516411120. Its totient is φ = 649890432.

The previous prime is 1056071983. The next prime is 1056072001. The reversal of 1056071991 is 1991706501.

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

It is not a de Polignac number, because 1056071991 - 2³ = 1056071983 is a prime.

It is a super-2 number, since 2×1056071991² = 2230576100349408162, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39), and also a Moran number because the ratio is a prime number: 27078769 = 1056071991 / (1 + 0 + 5 + 6 + 0 + 7 + 1 + 9 + 9 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1056071591) 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, 13539346 + ... + 13539423.

It is an arithmetic number, because the mean of its divisors is an integer number (189551390).

Almost surely, 2^1056071991 is an apocalyptic number.

1056071991 is a deficient number, since it is larger than the sum of its proper divisors (460339129).

1056071991 is a wasteful number, since it uses less digits than its factorization.

1056071991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27078785.

The product of its (nonzero) digits is 17010, while the sum is 39.

The square root of 1056071991 is about 32497.2612846067. The cubic root of 1056071991 is about 1018.3518143466.

The spelling of 1056071991 in words is "one billion, fifty-six million, seventy-one thousand, nine hundred ninety-one".