19961381 has 16 divisors (see below), whose sum is σ = 23112000. Its totient is φ = 17049600.

The previous prime is 19961371. The next prime is 19961393. The reversal of 19961381 is 18316991.

It is a cyclic number.

It is not a de Polignac number, because 19961381 - 2⁶ = 19961317 is a prime.

It is a super-2 number, since 2×19961381² = 796913462854322, which 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 (19961321) 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, 30821 + ... + 31461.

It is an arithmetic number, because the mean of its divisors is an integer number (1444500).

Almost surely, 2^19961381 is an apocalyptic number.

19961381 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

19961381 is a deficient number, since it is larger than the sum of its proper divisors (3150619).

19961381 is a wasteful number, since it uses less digits than its factorization.

19961381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 820.

The product of its digits is 11664, while the sum is 38.

The square root of 19961381 is about 4467.8161331908. The cubic root of 19961381 is about 271.2669355945.

The spelling of 19961381 in words is "nineteen million, nine hundred sixty-one thousand, three hundred eighty-one".