64781431 has 32 divisors (see below), whose sum is σ = 81204480. Its totient is φ = 50803200.

The previous prime is 64781419. The next prime is 64781443. The reversal of 64781431 is 13418746.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (64781419) and next prime (64781443).

It is a 9-Lehmer number, since φ(64781431) divides (64781431-1)⁹.

It is a cyclic number.

It is not a de Polignac number, because 64781431 - 2¹³ = 64773239 is a prime.

It is a super-2 number, since 2×64781431² = 8393267604815522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64781401) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 306916 + ... + 307126.

It is an arithmetic number, because the mean of its divisors is an integer number (2537640).

Almost surely, 2^64781431 is an apocalyptic number.

64781431 is a deficient number, since it is larger than the sum of its proper divisors (16423049).

64781431 is a wasteful number, since it uses less digits than its factorization.

64781431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 367.

The product of its digits is 16128, while the sum is 34.

The square root of 64781431 is about 8048.6912600745. The cubic root of 64781431 is about 401.6214000246.

The spelling of 64781431 in words is "sixty-four million, seven hundred eighty-one thousand, four hundred thirty-one".