31161620 has 48 divisors (see below), whose sum is σ = 75548928. Its totient is φ = 10575360.

The previous prime is 31161607. The next prime is 31161643. The reversal of 31161620 is 2616113.

It is a super-2 number, since 2×31161620² = 1942093122048800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 31161592 and 31161601.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13340 + ... + 15500.

It is an arithmetic number, because the mean of its divisors is an integer number (1573936).

Almost surely, 2^31161620 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31161620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37774464).

31161620 is an abundant number, since it is smaller than the sum of its proper divisors (44387308).

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

31161620 is a wasteful number, since it uses less digits than its factorization.

31161620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2280 (or 2278 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 31161620 is about 5582.2593992039. The cubic root of 31161620 is about 314.6830439104.

Adding to 31161620 its reverse (2616113), we get a palindrome (33777733).

The spelling of 31161620 in words is "thirty-one million, one hundred sixty-one thousand, six hundred twenty".