21887461621 has 2 divisors, whose sum is σ = 21887461622. Its totient is φ = 21887461620.

The previous prime is 21887461579. The next prime is 21887461633. The reversal of 21887461621 is 12616478812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21878551396 + 8910225 = 147914^2 + 2985^2 .

It is a cyclic number.

It is not a de Polignac number, because 21887461621 - 2¹³ = 21887453429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21887461721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10943730810 + 10943730811.

It is an arithmetic number, because the mean of its divisors is an integer number (10943730811).

Almost surely, 2^21887461621 is an apocalyptic number.

It is an amenable number.

21887461621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21887461621 is an equidigital number, since it uses as much as digits as its factorization.

21887461621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 258048, while the sum is 46.

The spelling of 21887461621 in words is "twenty-one billion, eight hundred eighty-seven million, four hundred sixty-one thousand, six hundred twenty-one".