31321620 has 96 divisors (see below), whose sum is σ = 106323840. Its totient is φ = 7591680.

The previous prime is 31321613. The next prime is 31321637. The reversal of 31321620 is 2612313.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 31321593 and 31321602.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3304 + ... + 8576.

It is an arithmetic number, because the mean of its divisors is an integer number (1107540).

Almost surely, 2^31321620 is an apocalyptic number.

31321620 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31321620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (53161920).

31321620 is an abundant number, since it is smaller than the sum of its proper divisors (75002220).

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

31321620 is a wasteful number, since it uses less digits than its factorization.

31321620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5302 (or 5294 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 31321620 is about 5596.5721651740. The cubic root of 31321620 is about 315.2207070019.

Adding to 31321620 its reverse (2612313), we get a palindrome (33933933).

It can be divided in two parts, 313216 and 20, that added together give a triangular number (313236 = T₇₉₁).

The spelling of 31321620 in words is "thirty-one million, three hundred twenty-one thousand, six hundred twenty".