12621661501 has 4 divisors (see below), whose sum is σ = 13028811904. Its totient is φ = 12214511100.

The previous prime is 12621661489. The next prime is 12621661531. The reversal of 12621661501 is 10516612621.

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 12621661501 - 2¹⁷ = 12621530429 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 407150371 = 12621661501 / (1 + 2 + 6 + 2 + 1 + 6 + 6 + 1 + 5 + 0 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12621661531) 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, 203575155 + ... + 203575216.

It is an arithmetic number, because the mean of its divisors is an integer number (3257202976).

Almost surely, 2^12621661501 is an apocalyptic number.

It is an amenable number.

12621661501 is a deficient number, since it is larger than the sum of its proper divisors (407150403).

12621661501 is an equidigital number, since it uses as much as digits as its factorization.

12621661501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407150402.

The product of its (nonzero) digits is 4320, while the sum is 31.

The spelling of 12621661501 in words is "twelve billion, six hundred twenty-one million, six hundred sixty-one thousand, five hundred one".