1534921981 has 4 divisors (see below), whose sum is σ = 1537244764. Its totient is φ = 1532599200.

The previous prime is 1534921979. The next prime is 1534921987. The reversal of 1534921981 is 1891294351.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1891294351 = 419 ⋅4513829.

It can be written as a sum of positive squares in 2 ways, for example, as 1360945881 + 173976100 = 36891^2 + 13190^2 .

It is a cyclic number.

It is not a de Polignac number, because 1534921981 - 2¹ = 1534921979 is a prime.

It is a super-2 number, since 2×1534921981² = 4711970975513928722, 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 (1534921987) 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, 1160400 + ... + 1161721.

It is an arithmetic number, because the mean of its divisors is an integer number (384311191).

Almost surely, 2^1534921981 is an apocalyptic number.

It is an amenable number.

1534921981 is a deficient number, since it is larger than the sum of its proper divisors (2322783).

1534921981 is an equidigital number, since it uses as much as digits as its factorization.

1534921981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2322782.

The product of its digits is 77760, while the sum is 43.

The square root of 1534921981 is about 39178.0803638974. The cubic root of 1534921981 is about 1153.5296673027.

The spelling of 1534921981 in words is "one billion, five hundred thirty-four million, nine hundred twenty-one thousand, nine hundred eighty-one".