156991770 has 160 divisors (see below), whose sum is σ = 481895568. Its totient is φ = 36329472.

The previous prime is 156991763. The next prime is 156991789. The reversal of 156991770 is 77199651.

156991770 is a `hidden beast` number, since 1 + 569 + 9 + 17 + 70 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 89472681 + 67519089 = 9459^2 + 8217^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 178572 + ... + 179448.

Almost surely, 2^156991770 is an apocalyptic number.

156991770 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 156991770, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (240947784).

156991770 is an abundant number, since it is smaller than the sum of its proper divisors (324903798).

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

156991770 is a wasteful number, since it uses less digits than its factorization.

156991770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 926 (or 917 counting only the distinct ones).

The product of its (nonzero) digits is 119070, while the sum is 45.

The square root of 156991770 is about 12529.6356690847. The cubic root of 156991770 is about 539.4596446546.

It can be divided in two parts, 1569 and 91770, that added together give a palindrome (93339).

The spelling of 156991770 in words is "one hundred fifty-six million, nine hundred ninety-one thousand, seven hundred seventy".