161621020 has 48 divisors (see below), whose sum is σ = 372613248. Its totient is φ = 58397760.

The previous prime is 161620957. The next prime is 161621029. The reversal of 161621020 is 20126161.

It is a super-2 number, since 2×161621020² = 52242708211680800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161621029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33607 + ... + 38113.

It is an arithmetic number, because the mean of its divisors is an integer number (7762776).

Almost surely, 2^161621020 is an apocalyptic number.

161621020 is a gapful number since it is divisible by the number (10) 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 161621020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (186306624).

161621020 is an abundant number, since it is smaller than the sum of its proper divisors (210992228).

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

161621020 is a wasteful number, since it uses less digits than its factorization.

161621020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4690 (or 4688 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 161621020 is about 12713.0256036870. The cubic root of 161621020 is about 544.7107518815.

Adding to 161621020 its reverse (20126161), we get a palindrome (181747181).

The spelling of 161621020 in words is "one hundred sixty-one million, six hundred twenty-one thousand, twenty".