15621961 has 4 divisors (see below), whose sum is σ = 15886800. Its totient is φ = 15357124.

The previous prime is 15621959. The next prime is 15621967. The reversal of 15621961 is 16912651.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16912651 = 7 ⋅2416093.

It is a cyclic number.

It is not a de Polignac number, because 15621961 - 2¹ = 15621959 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15621967) 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, 132331 + ... + 132448.

It is an arithmetic number, because the mean of its divisors is an integer number (3971700).

Almost surely, 2^15621961 is an apocalyptic number.

It is an amenable number.

15621961 is a deficient number, since it is larger than the sum of its proper divisors (264839).

15621961 is an equidigital number, since it uses as much as digits as its factorization.

15621961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 264838.

The product of its digits is 3240, while the sum is 31.

The square root of 15621961 is about 3952.4626500449. The cubic root of 15621961 is about 249.9837909491.

The spelling of 15621961 in words is "fifteen million, six hundred twenty-one thousand, nine hundred sixty-one".