1621090121 has 4 divisors (see below), whose sum is σ = 1852674432. Its totient is φ = 1389505812.

The previous prime is 1621090109. The next prime is 1621090123. The reversal of 1621090121 is 1210901261.

It is a happy number.

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 not a de Polignac number, because 1621090121 - 2¹⁴ = 1621073737 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1621090123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 115792145 + ... + 115792158.

It is an arithmetic number, because the mean of its divisors is an integer number (463168608).

Almost surely, 2^1621090121 is an apocalyptic number.

It is an amenable number.

1621090121 is a deficient number, since it is larger than the sum of its proper divisors (231584311).

1621090121 is an equidigital number, since it uses as much as digits as its factorization.

1621090121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 231584310.

The product of its (nonzero) digits is 216, while the sum is 23.

The square root of 1621090121 is about 40262.7634545867. The cubic root of 1621090121 is about 1174.7236702843.

Adding to 1621090121 its reverse (1210901261), we get a palindrome (2831991382).

The spelling of 1621090121 in words is "one billion, six hundred twenty-one million, ninety thousand, one hundred twenty-one".