1621511825 has 12 divisors (see below), whose sum is σ = 2018157660. Its totient is φ = 1292381760.

The previous prime is 1621511807. The next prime is 1621511831. The reversal of 1621511825 is 5281151261.

It is a Cunningham number, because it is equal to 40268²+1.

It can be written as a sum of positive squares in 6 ways, for example, as 966289 + 1620545536 = 983^2 + 40256^2 .

It is not a de Polignac number, because 1621511825 - 2¹⁰ = 1621510801 is a prime.

It is a super-2 number, since 2×1621511825² = 5258601197229661250, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1621511791 and 1621511800.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 113834 + ... + 127283.

It is an arithmetic number, because the mean of its divisors is an integer number (168179805).

Almost surely, 2^1621511825 is an apocalyptic number.

It is an amenable number.

1621511825 is a deficient number, since it is larger than the sum of its proper divisors (396645835).

1621511825 is a wasteful number, since it uses less digits than its factorization.

1621511825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 241396 (or 241391 counting only the distinct ones).

The product of its digits is 4800, while the sum is 32.

The square root of 1621511825 is about 40268.0000124168. Note that the first 4 decimals coincide. The cubic root of 1621511825 is about 1174.8255241160.

The spelling of 1621511825 in words is "one billion, six hundred twenty-one million, five hundred eleven thousand, eight hundred twenty-five".