1629011981 has 2 divisors, whose sum is σ = 1629011982. Its totient is φ = 1629011980.

The previous prime is 1629011971. The next prime is 1629011999. The reversal of 1629011981 is 1891109261.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1085702500 + 543309481 = 32950^2 + 23309^2 .

It is an emirp because it is prime and its reverse (1891109261) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1629011981 - 2¹⁴ = 1628995597 is a prime.

It is a super-2 number, since 2×1629011981² = 5307360068483088722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1629011921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 814505990 + 814505991.

It is an arithmetic number, because the mean of its divisors is an integer number (814505991).

Almost surely, 2^1629011981 is an apocalyptic number.

It is an amenable number.

1629011981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1629011981 is an equidigital number, since it uses as much as digits as its factorization.

1629011981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 38.

The square root of 1629011981 is about 40361.0205644010. The cubic root of 1629011981 is about 1176.6340881909.

The spelling of 1629011981 in words is "one billion, six hundred twenty-nine million, eleven thousand, nine hundred eighty-one".