31421820 has 96 divisors (see below), whose sum is σ = 94913280. Its totient is φ = 7741440.

The previous prime is 31421813. The next prime is 31421827. The reversal of 31421820 is 2812413.

It is an interprime number because it is at equal distance from previous prime (31421813) and next prime (31421827).

It is a super-2 number, since 2×31421820² = 1974661544224800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31421827) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 48700 + ... + 49340.

It is an arithmetic number, because the mean of its divisors is an integer number (988680).

Almost surely, 2^31421820 is an apocalyptic number.

31421820 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 31421820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47456640).

31421820 is an abundant number, since it is smaller than the sum of its proper divisors (63491460).

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

31421820 is a wasteful number, since it uses less digits than its factorization.

31421820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 715 (or 713 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 31421820 is about 5605.5169253156. The cubic root of 31421820 is about 315.5564867136.

The spelling of 31421820 in words is "thirty-one million, four hundred twenty-one thousand, eight hundred twenty".