20212561621 has 16 divisors (see below), whose sum is σ = 25522331904. Its totient is φ = 15596976384.

The previous prime is 20212561619. The next prime is 20212561661. The reversal of 20212561621 is 12616521202.

It is not a de Polignac number, because 20212561621 - 2¹ = 20212561619 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 20212561621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20212561661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3689730 + ... + 3695203.

It is an arithmetic number, because the mean of its divisors is an integer number (1595145744).

Almost surely, 2^20212561621 is an apocalyptic number.

It is an amenable number.

20212561621 is a deficient number, since it is larger than the sum of its proper divisors (5309770283).

20212561621 is a wasteful number, since it uses less digits than its factorization.

20212561621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7384980.

The product of its (nonzero) digits is 2880, while the sum is 28.

The spelling of 20212561621 in words is "twenty billion, two hundred twelve million, five hundred sixty-one thousand, six hundred twenty-one".