1621235261 has 4 divisors (see below), whose sum is σ = 1621636800. Its totient is φ = 1620833724.

The previous prime is 1621235251. The next prime is 1621235269. The reversal of 1621235261 is 1625321261.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1621235261 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621235269) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 194651 + ... + 202808.

It is an arithmetic number, because the mean of its divisors is an integer number (405409200).

Almost surely, 2^1621235261 is an apocalyptic number.

It is an amenable number.

1621235261 is a deficient number, since it is larger than the sum of its proper divisors (401539).

1621235261 is an equidigital number, since it uses as much as digits as its factorization.

1621235261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401538.

The product of its digits is 4320, while the sum is 29.

The square root of 1621235261 is about 40264.5658240592. The cubic root of 1621235261 is about 1174.7587278264.

The spelling of 1621235261 in words is "one billion, six hundred twenty-one million, two hundred thirty-five thousand, two hundred sixty-one".