1373551621 has 16 divisors (see below), whose sum is σ = 1545410160. Its totient is φ = 1212019200.

The previous prime is 1373551607. The next prime is 1373551633. The reversal of 1373551621 is 1261553731.

It can be written as a sum of positive squares in 8 ways, for example, as 170433025 + 1203118596 = 13055^2 + 34686^2 .

It is a 5-Lehmer number, since φ(1373551621) divides (1373551621-1)⁵.

It is a cyclic number.

It is not a de Polignac number, because 1373551621 - 2¹³ = 1373543429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1373551681) 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, 20041 + ... + 56113.

It is an arithmetic number, because the mean of its divisors is an integer number (96588135).

Almost surely, 2^1373551621 is an apocalyptic number.

It is an amenable number.

1373551621 is a deficient number, since it is larger than the sum of its proper divisors (171858539).

1373551621 is a wasteful number, since it uses less digits than its factorization.

1373551621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36216.

The product of its digits is 18900, while the sum is 34.

The square root of 1373551621 is about 37061.4573512699. The cubic root of 1373551621 is about 1111.5994637398.

It can be divided in two parts, 13735 and 51621, that added together give a palindrome (65356).

The spelling of 1373551621 in words is "one billion, three hundred seventy-three million, five hundred fifty-one thousand, six hundred twenty-one".