1540721438 has 16 divisors (see below), whose sum is σ = 2433984720. Its totient is φ = 729435456.

The previous prime is 1540721423. The next prime is 1540721461. The reversal of 1540721438 is 8341270451.

It is a junction number, because it is equal to n+sod(n) for n = 1540721398 and 1540721407.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 71720 + ... + 90692.

It is an arithmetic number, because the mean of its divisors is an integer number (152124045).

Almost surely, 2^1540721438 is an apocalyptic number.

1540721438 is a deficient number, since it is larger than the sum of its proper divisors (893263282).

1540721438 is a wasteful number, since it uses less digits than its factorization.

1540721438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21131.

The product of its (nonzero) digits is 26880, while the sum is 35.

The square root of 1540721438 is about 39252.0246356796. The cubic root of 1540721438 is about 1154.9806504632.

Adding to 1540721438 its reverse (8341270451), we get a palindrome (9881991889).

The spelling of 1540721438 in words is "one billion, five hundred forty million, seven hundred twenty-one thousand, four hundred thirty-eight".