1861037621 has 4 divisors (see below), whose sum is σ = 1866027372. Its totient is φ = 1856047872.

The previous prime is 1861037611. The next prime is 1861037641. The reversal of 1861037621 is 1267301681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1267301681 = 73 ⋅17360297.

It can be written as a sum of positive squares in 2 ways, for example, as 534256996 + 1326780625 = 23114^2 + 36425^2 .

It is a cyclic number.

It is not a de Polignac number, because 1861037621 - 2¹⁴ = 1861021237 is a prime.

It is a super-2 number, since 2×1861037621² = 6926922053554679282, 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 (1861037611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2494316 + ... + 2495061.

It is an arithmetic number, because the mean of its divisors is an integer number (466506843).

Almost surely, 2^1861037621 is an apocalyptic number.

It is an amenable number.

1861037621 is a deficient number, since it is larger than the sum of its proper divisors (4989751).

1861037621 is an equidigital number, since it uses as much as digits as its factorization.

1861037621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4989750.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 1861037621 is about 43139.7452588677. The cubic root of 1861037621 is about 1230.0375913335.

The spelling of 1861037621 in words is "one billion, eight hundred sixty-one million, thirty-seven thousand, six hundred twenty-one".