1621624861 has 4 divisors (see below), whose sum is σ = 1621805724. Its totient is φ = 1621444000.

The previous prime is 1621624841. The next prime is 1621624889. The reversal of 1621624861 is 1684261261.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1158040900 + 463583961 = 34030^2 + 21531^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621624861 - 2²¹ = 1619527709 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1621624861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621624801) 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, 76240 + ... + 95161.

It is an arithmetic number, because the mean of its divisors is an integer number (405451431).

Almost surely, 2^1621624861 is an apocalyptic number.

It is an amenable number.

1621624861 is a deficient number, since it is larger than the sum of its proper divisors (180863).

1621624861 is an equidigital number, since it uses as much as digits as its factorization.

1621624861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180862.

The product of its digits is 27648, while the sum is 37.

The square root of 1621624861 is about 40269.4035341970. The cubic root of 1621624861 is about 1174.8528226099.

The spelling of 1621624861 in words is "one billion, six hundred twenty-one million, six hundred twenty-four thousand, eight hundred sixty-one".