1621854990 has 96 divisors (see below), whose sum is σ = 4880378880. Its totient is φ = 366005952.

The previous prime is 1621854979. The next prime is 1621855019. The reversal of 1621854990 is 994581261.

1621854990 is a `hidden beast` number, since 1 + 6 + 2 + 18 + 549 + 90 = 666.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 33477 + ... + 66063.

It is an arithmetic number, because the mean of its divisors is an integer number (50837280).

Almost surely, 2^1621854990 is an apocalyptic number.

1621854990 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 1621854990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2440189440).

1621854990 is an abundant number, since it is smaller than the sum of its proper divisors (3258523890).

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

1621854990 is a wasteful number, since it uses less digits than its factorization.

1621854990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32686 (or 32683 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 45.

The square root of 1621854990 is about 40272.2608007050. The cubic root of 1621854990 is about 1174.9083954540.

The spelling of 1621854990 in words is "one billion, six hundred twenty-one million, eight hundred fifty-four thousand, nine hundred ninety".