20621985061 has 4 divisors (see below), whose sum is σ = 20649740832. Its totient is φ = 20594229292.

The previous prime is 20621985017. The next prime is 20621985067. The reversal of 20621985061 is 16058912602.

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 a de Polignac number, because none of the positive numbers 2^k-20621985061 is a prime.

It is a super-2 number, since 2×20621985061² (a number of 21 digits) 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 (20621985067) 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, 13876771 + ... + 13878256.

It is an arithmetic number, because the mean of its divisors is an integer number (5162435208).

Almost surely, 2^20621985061 is an apocalyptic number.

It is an amenable number.

20621985061 is a deficient number, since it is larger than the sum of its proper divisors (27755771).

20621985061 is an equidigital number, since it uses as much as digits as its factorization.

20621985061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27755770.

The product of its (nonzero) digits is 51840, while the sum is 40.

The spelling of 20621985061 in words is "twenty billion, six hundred twenty-one million, nine hundred eighty-five thousand, sixty-one".