1928921621 has 6 divisors (see below), whose sum is σ = 2120219766. Its totient is φ = 1753565000.

The previous prime is 1928921597. The next prime is 1928921647. The reversal of 1928921621 is 1261298291.

It can be written as a sum of positive squares in only one way, i.e., 1063738225 + 865183396 = 32615^2 + 29414^2 .

It is not a de Polignac number, because 1928921621 - 2⁶ = 1928921557 is a prime.

It is a super-2 number, since 2×1928921621² = 7441477239922535282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1928921221) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7970630 + ... + 7970871.

It is an arithmetic number, because the mean of its divisors is an integer number (353369961).

Almost surely, 2^1928921621 is an apocalyptic number.

1928921621 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1928921621 is a deficient number, since it is larger than the sum of its proper divisors (191298145).

1928921621 is a wasteful number, since it uses less digits than its factorization.

1928921621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15941523 (or 15941512 counting only the distinct ones).

The product of its digits is 31104, while the sum is 41.

The square root of 1928921621 is about 43919.4902178976. The cubic root of 1928921621 is about 1244.8151359631.

The spelling of 1928921621 in words is "one billion, nine hundred twenty-eight million, nine hundred twenty-one thousand, six hundred twenty-one".