20401537 has 4 divisors (see below), whose sum is σ = 21970900. Its totient is φ = 18832176.

The previous prime is 20401523. The next prime is 20401553. The reversal of 20401537 is 73510402.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7376656 + 13024881 = 2716^2 + 3609^2 .

It is a cyclic number.

It is not a de Polignac number, because 20401537 - 2¹⁵ = 20368769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20402537) 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, 784662 + ... + 784687.

It is an arithmetic number, because the mean of its divisors is an integer number (5492725).

Almost surely, 2^20401537 is an apocalyptic number.

It is an amenable number.

20401537 is a deficient number, since it is larger than the sum of its proper divisors (1569363).

20401537 is a wasteful number, since it uses less digits than its factorization.

20401537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1569362.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 20401537 is about 4516.8060618096. The cubic root of 20401537 is about 273.2463036760.

Adding to 20401537 its reverse (73510402), we get a palindrome (93911939).

It can be divided in two parts, 204015 and 37, that multiplied together give a triangular number (7548555 = T₃₈₈₅).

The spelling of 20401537 in words is "twenty million, four hundred one thousand, five hundred thirty-seven".